Healthy African American Controls Research Articles

Transcriptional Inflammatory Signatures Differentiate Baseline Health from Acute Pain in Sickle Cell Disease Patients

Severe unpredictable acute pain and chronic daily pain causes significant morbidity for individuals with sickle cell disease (SCD). SCD is shown to be a chronic inflammatory disorder. Regulation of the immune response can potentially modulate the inflammatory impact on pain in SCD. We sought to determine the balance between patients’ inflammatory and immune regulatory response and examine whether this balance changes during acute SCD pain. We conducted a cross sectional analysis involving 3 cohorts: 16 SCD patients in baseline health, 27 SCD patients during acute pain and 45 healthy African American controls. Participant plasma was co-cultured with cryopreserved PBMCs from a healthy donor to induce transcription. We identified transcripts that differentiate SCD patients from healthy controls and retained ones differentially expressed that exhibit a fold change >1.4, ANOVA p-value of

Plasma-Based Inflammatory Signatures in Patients with Sickle Cell Disease during Baseline Health and Acute Pain

INTRODUCTION: Pain, the most common complication of sickle cell disease (SCD), presents as both sudden acute pain and chronic daily pain. However, there is wide variability in frequency and presentation of pain despite inheritance of the same monogenic gene defect. SCD has long been recognized as a chronic inflammatory condition. The ongoing effect of repeated vaso-occlusion, ischemia-reperfusion injury and hemolysis contribute to further SCD inflammation and likely pain. Regulation of the immune response can potentially modulate the inflammatory impact on pain. The collective balance of these inflammatory mediators in union in SCD patients and how this balance may change during baseline health and acute pain is unknown. The objective of this work was to determine the balance between patients' inflammatory and immune regulatory response and examine whether this balance changes during acute pain in patients with SCD. METHODS: We conducted a cross sectional analysis involving 3 cohorts: patients with SCD who were in their baseline health state, patients with SCD who had an acute pain episode and healthy African American controls. We used a novel bioassay originally developed for use in type 1 diabetes and applied to cystic fibrosis, inflammatory bowel disease and influenza to determine the inflammatory/immune regulatory response. This response was calculated as a composite Inflammatory Index (I.I.com) from these 3 patient cohorts. Patient plasma was co-cultured with cryopreserved PBMCs from a healthy donor to induce transcription (Figure 1). We identified informative transcripts that differentiate SCD patients from healthy controls thereby defining the disease-specific plasma-induced signature and retained ones differentially expressed between patients with SCD and controls that exhibit a fold change >1.4, ANOVA p-value of <0.05 and an FDR <10%. The data were subjected to ontological analyses for quantitative interpretation with Database for Annotation, Visualization and Integrated Discovery (DAVID) and Ingenuity Pathway Analysis (IPA). Our scoring strategy used the degree of induction of genes in inflammatory and regulatory ontological classes. The composite I.I.com was calculated using the average ratio between the mean log intensity of the genes classified as being "inflammatory" versus "regulatory". Independent samples Student's t-test was used to compare the mean I.I.com between 1) SCD baseline health cohort and controls and 2) SCD baseline health cohort and SCD acute pain cohort. RESULTS: Plasma from 16 patients with SCD in baseline health, 27 patients with SCD with an acute pain episode, and 45 African American controls were collected and analyzed. The average age of the study population was 12.6 (SD=3.6) years old and 52.3% were female. Quantitative scoring of plasma-induced signatures showed SCD patients had significantly higher mean I.I.com during baseline health compared to controls (0.713 vs. -1.235-12, p=5.4625-11). In addition, patients with SCD during acute pain episodes had significantly higher I.I.com than patients in baseline health (1.282 vs. 0.713, p=5.2051-8) (Figure 2). Heat map in Figure 3 shows differential gene expression between the cohorts; green and red colors in heat maps represent lower or higher relative expression respectively. CONCLUSION: Our findings show distinct immune signatures in SCD patients compared to controls and distinct signatures in SCD patients during acute pain episodes as compared to baseline health. The novel assay used to assess the inflammatory and immune regulatory gene expression in the three cohorts studied allowed for the determination of the balance between the two immune states. The imbalance between inflammation and immune regulation shown in our results in SCD patients of SCD pain. Further investigation into the specific inflammatory pathways that contribute to altered immune response could lead to novel targets for pain treatment. Disclosures Mucalo: NIH/NINDS: Research Funding; NIH/NHLBI: Research Funding. Jia:NIH/NHBLI: Research Funding; NIH/NINDS: Research Funding. Panepinto:NINDS: Research Funding; HRSA: Research Funding; NINDS: Research Funding; NHLBI: Research Funding. Roethle:NIH/NHLBI: Research Funding; NIH/NINDS: Research Funding. Hessner:NIH/NHLBI: Research Funding; NIH/NINDS: Research Funding. Brandow:NIH / NHLBI: Research Funding; Greater Milwaukee Foundation: Research Funding.

Long-Term Hydroxyurea Use Is Associated with Lower Levels of Hematopoietic Stem and Progenitor Cells in Patients with Sickle Cell Disease

Background Sickle cell disease (SCD) is curable by transplantation and potentially by gene therapy, and is generally treated by a combination of blood transfusion and Hydroxyurea (HU). Characterizing the hematopoietic system in SCD patients is important because the long-term effect of HU treatment are not known, and because of lower than expected efficacy of transduction and transplantation in Hematopoietic Stem and Progenitor Cells (HSPCs) in recent gene therapy trials. Previous studies have shown that the number of bone marrow (BM) CD34+ cells is elevated in SCD patients and that HU treatment is associated with decreased level of CD34+ cells in the peripheral blood (PB) and BM relative to steady state patients. However, hematopoiesis in SCD patients naive or treated with HU or transfusion remains poorly understood. Here, we report on the characterization of the HSPC compartment in patients with SCD by prospective isolation of 49f+ long-term Hematopoietic Stem Cells (49f+LT-HSCs), Multipotent Progenitors (MPPs), Common Myeloid Progenitors (CMPs), Megakaryocyte-Erythroid Progenitors (MEPs), and Granulocyte-Monocyte Progenitors (GMPs). Methods After obtaining consent, PB and/or BM were collected from 69 patients with HBSS/SB0, aged 12 to 45years, and 25 healthy adult African American controls. Patients were divided into chronic transfusion therapy (n=19), HU (n=31) and naïve (n=19) groups. Frozen mono-nuclear cells were analyzed by flow cytometry on a BD LSRII using CD 49f, 90 45Ra, 123, 235a, 38, 34, 33 and lineage antibodies. Results FACS analysis revealed that the number PB CD34+ cells was 2.5 CD34+/uL of blood in the HU group as compared to 19 CD34+/uL in the exchange and naive groups, and 7.3 CD34+/uL in the control group (q-value <0.05 in all cases). Analysis with additional markers revealed that the decrease in circulating HSPCs in the HU group affected the entire hematopoietic system since the number of 49f+LT-HSCs, MPPs, CMPs, MEPs were all significantly lower in the HU group. The decrease in cell number in the HU group, however, was not homogeneous. The proportion of LT-HSCs was higher in the HU and transfusion groups when compared to the naive and control groups. The HU group also had the lowest proportion of MPPs and GMPs, as well as the highest proportion of MEPs. We then investigated hematopoiesis as a function of the length of HU treatment to elucidate the long-term treatment effect of this cytotoxic agent. Patients > 18 years of age that had been treated on HU for at least three years exhibited a strong statistically significant negative correlation between years on HU and CD34+/uL (R2 = 0.41), LT-HSC/uL (R2 = 0.35), MPP/uL (R2 =0.43), CMP/uL (R2 = 0.37), MEP/uL (R2 = 0.25) and GMP/uL (R2 0.39, p<0.01 in all cases). Importantly there was no correlation between WBC counts, age, HU dose, or serum erythropoietin level versus the numbers of any HSPC/uL. Lastly, we compared the number of HSPCs in paired PB and BM samples 10 controls and 4 SCD patients. This revealed that the numbers of CD34+, HSCs, MPPs, CMPs, GMPs and MEPs in the PB and BM were well correlated (r2 in 0.6-0.8 range) suggesting that in first approximation, results obtained in the PB reflect changes in the BM rather than changes in egress of HSPCs from the BM. Discussion We have observed lower numbers of circulating CD34+,49f+LT- HSCs, MPPs, CMP, GMP and MEPs in individuals with HBSS on HU therapy when compared to naive, chronic transfusion and, to a lesser extent, controls. Furthermore we observed subtle differences in the proportion of various circulating stem and progenitor cells (HSPCs) suggesting that the various treatments affects hematopoiesis in complex ways. The strong negative correlations between the length of HU treatment and the numbers of HSPCs can be explained either by decreased cell mobilization to the periphery, or by a depletion of the HSPC numbers in the BM overtime. Most patients undergoing gene therapy trials are currently taken off HU and placed on transfusion therapy for several months to increase CD34+ cell collection and LT-HSC transduction efficiency. We observed a greater number of circulating 49f+LT-HSC/uL of blood in the transfusion group than in the HU group, but the proportion of 49f+LT-HSC relative to the number of CD34+ were similar in both groups. Functional studies may help determine whether 49f+LT-HSCs from the transfusion group are qualitatively different from of the HU group and more amenable to gene therapy. Figure Disclosures Manwani: Novartis: Consultancy; Pfizer: Consultancy; GBT: Consultancy, Research Funding. Minniti:Doris Duke Foundation: Research Funding.

Empirical model of human blood transverse relaxation at 3 T improves MRI T2 oximetry.

We sought a human blood T2 -oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T2 relaxation under spin tagging (TRUST). Blood was drawn from five healthy control subjects. Ninety-three in vitro blood transverse relaxation (T2b ) measurements were performed at 37°C over a broad range of hematocrits (10-55%) and oxygen saturations (14-100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes. 1/T2 rose linearly with hematocrit (r2 = 0.96), for fully saturated blood. Upon desaturation, 1/T2 rose linearly with the square of the oxygen extraction, (1-Y)2 , and the slope was linearly proportional to hematocrit (r2 = 0.88). The resulting bilinear model between 1/T2 , (1-Y)2 , and hematocrit had a combined r2 of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was -6% (absolute saturation) for hematocrits near 30% and rose to + 6% for hematocrits near 45%. This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364-2371, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

The Neuropeptide Substance P Is Elevated in Patients with Sickle Cell Disease

Patients with sickle cell disease (SCD) experience increased pain to thermal (cold, heat) stimuli compared to healthy controls suggesting peripheral and/or central sensitization. However, the underlying etiology of this thermal hypersensitivity is unknown. Substance P (SP), a primary pain neurotransmitter, is a potent mediator of neurogenic inflammation where inflammatory cell activation, vasodilation, and edema occur after the stimulation of sensory nerve fibers. Chronic elevation of SP can sensitize peripheral nociceptors resulting in thermal hypersensitivity and chronic neuropathic pain as shown in mice and humans without SCD and in SCD mice. Little is known about SP levels in patients with SCD in baseline health compared to healthy African American controls. Furthermore, little is known about changes in SP levels during acute SCD pain. The objective of this study was to evaluate plasma SP levels in SCD patients and controls in baseline health and in SCD patients during acute pain. We hypothesized that SCD patients, in baseline health, will have significantly higher SP levels compared to controls suggesting chronic pain sensitization and that SP levels will significantly increase during acute pain.Patients with SCD in baseline health and during admission for acute pain and healthy African American controls were recruited. Our primary outcome was plasma SP level measured in 3 independent cohorts: healthy African American controls, SCD patients in baseline heath, and SCD patients during acute pain. Plasma samples were assayed in duplicate for SP levels using competitive enzyme-linked immunosorbent assay (Cayman Chemical). Independent samples student's t-test was used to compare SP levels between: 1) SCD patients in baseline health and controls and 2) SCD patients in baseline health and those in acute pain. Multivariable linear regression analysis was used to determine the impact of age and gender on SP levels in the 3 independent groups.Thirty-five African American controls, 25 SCD patients in baseline health, and 12 SCD patients during acute pain completed the study. Controls were older than SCD patients in baseline health (mean (SD) age 21.5 (12.5) vs. 11.8 (3.8) yrs, p=0.0004) and there was no difference in the mean age of SCD patients in baseline health compared to those in acute pain (11.8 (3.8) vs. 12.1 (3.5) yrs, p=0.81). Gender did not differ between the same comparison groups. Genotypes of SCD groups were: 1) baseline: 68% SS, 24% SC, 8% Sβ+thal and 2) acute pain: 67% SS, 25% SC, 8% SOArab. The mean (SD) SP level of SCD patients in baseline health was significantly higher than controls (32.4 (11.6) vs. 22.9 (7.6) pg/mL, p=0.0009) (Figure 1). When controls were restricted to patients less than 19 years of age (n=21) to better match SCD patients in baseline health, the significant elevation of SP levels in SCD patients persisted (32.4 (11.5) vs. 21 (7.1) pg/mL, p<0.0001). Mean SP levels were even higher during acute SCD pain compared to SP levels of SCD patients at baseline (78.1 (43.4) vs. 32.4 (11.6) pg/mL, p=0.004) (Figure 1). Age and gender were not associated with differences in SP levels in controls or in SCD patients at baseline or during acute pain.The elevated SP levels in SCD patients during baseline health compared to controls suggests that SP may be a mediator of or marker for chronic pain sensitization. SP levels further increase during acute pain suggesting that SP may also play a role in mediating or marking an acute pain event. The downstream effects of chronically increased levels of SP on the development and propagation of pain in patients with SCD warrant further investigation. Ultimately, SP could differentiate those at risk for development of chronic pain and could be used as a novel biomarker for acute pain and resolution of a painful event. Eventually, compounds aimed at decreasing SP levels or blocking the SP receptor could be a target for novel treatments for SCD pain. [Display omitted] DisclosuresBrandow:NIH, ASH: Research Funding. Hillery:NIH: Research Funding. Panepinto:NKT Therapeutics, Inc: Consultancy; HRSA, NIH: Research Funding.

Clinically Meaningful Interpretation of Quantitative Sensory Testing As a Measure of Pain Sensitivity in Patients with Sickle Cell Disease

Patients with sickle cell disease (SCD) display hypersensitivity to thermal and/or mechanical stimuli compared to healthy controls when assessed with quantitative sensory testing (QST) suggesting impaired pain sensitivity. Impaired pain sensitivity is present when a defined stimulus (cold, heat, mechanical) produces exaggerated pain in a patient compared to healthy controls and suggests pain processing abnormalities in the peripheral and/or central nervous system. Existing studies report significant differences in mean/median thermal and/or mechanical pain thresholds between SCD patients and healthy controls. However, for clinical purposes it is important to understand if an individual patient meets criteria for impaired pain sensitivity. To date, thresholds above or below which a patient is defined as having impaired pain sensitivity have not been established in pediatric SCD patients. We sought to: 1) define thresholds for impaired cold, heat, and mechanical pain sensitivity in SCD patients ages ≥7 years and 2) determine the proportion of SCD patients meeting criteria for impaired pain sensitivity with each testing modality. Our secondary objective was to compare age, gender and prior history of pain between patients with and without impaired pain sensitivity.We conducted a cross-sectional study of SCD patients and healthy African American controls ages ≥ 7 years. Using QST we assessed cold, heat, and mechanical pain thresholds via the method of limits on the thenar eminence of the non-dominant hand and lateral dorsum of foot (randomized). Our primary outcome was threshold for impaired pain sensitivity defined as: 1) cold pain threshold that was one standard deviation (SD) above median cold pain threshold in the control group; 2) heat pain threshold that was one SD below median heat pain threshold in the control group; 3) mechanical pain threshold that was one SD below median mechanical pain threshold in the control group. Data were skewed so bootstrap resampling was used to obtain the 95% CI for the median that is congruent with the SD of the median. Mann-Whitney Test and Pearson Chi-square were used to compare age, gender, and prior history of pain (total number of lifetime emergency department visits and/or hospitalizations) between those with and without impaired pain sensitivity.A total of 55 SCD patients and 57 African American controls completed QST. There were no differences in mean±SD age (15.4±6.3 vs. 16.3±10.2 yrs, p=0.59) or gender (60% vs. 56% female, p=0.68) between groups. SCD genotypes were: 67% SS, 18% SC, 11% Sβ+ thal, 4% other. Table 1 displays thresholds for impaired pain sensitivity and proportions of SCD patients meeting criteria for impaired pain sensitivity. We found 21.8% (n=12) of SCD patients had impaired pain sensitivity with all 3 testing modalities and the majority (81.8%, n=45) had impaired pain sensitivity with one or more testing modalities. Only 18.2% (n=20) had no evidence of impaired pain sensitivity. There was no difference in median age, gender, or median number of pain encounters between those with and without impaired pain sensitivity (15 (IQR 10.5-19) vs. 13.5 yrs (IQR 11-21.5), p=0.939; 60% female in both groups; number of pain encounters: 9 (IQR 4-23.5) vs. 3 (IQR 0.25-19.8), p=0.132).Determining a threshold for impaired pain sensitivity is clinically meaningful. Using QST data, we established thresholds for impaired cold, heat and mechanical pain sensitivity. Based on these thresholds, almost a quarter of SCD patients were impaired in all 3 modalities tested and the majority were impaired in at least one modality. Impaired cold pain sensitivity was the most common finding supporting epidemiological data that increased numbers of pain events are associated with colder temperatures. If used clinically, QST could serve as a screening tool to phenotype SCD pain, guide further evaluation of the etiology of pain, guide treatment decisions, or serve as an outcome for an intervention aimed at altering pain sensitivity.Table 1Thresholds for Impaired Pain Sensitivity and Proportion of SCD Patients with Impaired Pain Sensitivity (n=55)Threshold*Proportion ImpairedHandCold Pain Threshold>17.01ºC63.6% (n=35)Heat Pain Threshold<43.91ºC60% (n=33)Mechanical Pain Threshold<4.42 g41.8% (n=23)FootCold Pain Threshold>21.75ºC58.2% (n=32)Heat Pain Threshold<42.39ºC40% (n=22)Mechanical Pain Threshold<7.29 g54.5% (n=30)*1 SD from Control Median DisclosuresBrandow:NIH, ASH: Research Funding. Panepinto:HRSA, NIH: Research Funding; NKT Therapeutics, Inc: Consultancy.

Expression of Interferon-γ Receptor Genes in Peripheral Blood Mononuclear Cells Is Associated With Rheumatoid Arthritis and Its Radiographic Severity in African Americans.

The factors responsible for radiographic severity in African American patients with rheumatoid arthritis (RA) are poorly understood. We sought to identify genes whose expression in peripheral blood mononuclear cells is associated with radiographic severity in RA. In the first phase of the study, we performed real-time quantitative polymerase chain reaction to analyze the expression of 182 candidate genes in 40 African American RA patients with extremes of radiographic damage (low versus high radiographic scores) and disease duration (≤2 years versus >2 years) and 20 healthy African American control subjects; the genes were selected based on plausible immune pathways. In the second phase, we analyzed the expression of the genes that were shown to be significantly associated with radiographic scores in 576 African American patients with RA and 51 African American control subjects who had not been studied previously, accounting for autoantibody status and disease duration. We observed significant differences in IFNGR1 expression between patients with RA and control subjects (adjusted P [P(adj)] = 6 × 10(-14)) and in IFNGR2 expression between RA patients with erosions and those with no erosions (P(adj) = 0.01 by Wilcoxon's rank sum test). We also observed significant correlations between IFNGR2 expression and radiographic scores (P(adj) = 0.03 for erosions, P(adj) = 0.04 for joint space narrowing, and P(adj) = 0.03 for total radiographic score [zero-inflated negative binomial regression model]) and annualized progression rate (P(adj) = 0.0024 by Spearman's correlation analysis). These findings have important implications with respect to the role of interferon-γ (IFNγ) in the pathogenesis of RA and may lead to identification of a biomarker for radiographic damage. Additional studies are needed to define the cell subsets responsible for the association of IFNγ receptor gene expression with radiographic findings, which downstream mechanisms are involved, and generalizability to other RA populations.

Higher Levels of Circulating Fibrocytes Are Associated with Lower Oxygen Saturation in Adults with Sickle Cell Disease

Background: In patients with sickle cell disease (SCD), tissue injury due to vaso-occlusion can result in fibrosis and organ dysfunction. Fibrocytes are circulating bone marrow-derived cells that can home to damaged organs, differentiate into fibroblasts and myofibroblasts and contribute to scarring. Fibrocytes have been implicated in the pathogenesis of pulmonary fibrosis in several animal models, including a mouse model of SCD. A preliminary study of patients with SCD suggests that the concentration of circulating fibrocytes is increased compared to controls. To build upon these findings, we tested the hypothesis that in adults with SCD higher levels of fibrocytes are associated with measures of lung disease.Methods: In a prospective cohort study of steady state adults with SCD, peripheral blood fibrocytes were measured and subjects underwent a pulmonary assessment that included pulmonary function tests, resting pulse oximetry, a 6-minute walk test, 2-D echocardiography, and high-resolution chest CT. A control group of healthy, African Americans also provided fibrocyte measurements and had pulmonary function testing. Fibrocytes were identified as collagen-1+ CD45+ cells using quantitative flow cytometry. For statistical analyses, fibrocyte values were log-transformed. Continuous and dichotomous variables were tested with Pearson’s correlation and Mann-Whitney U, respectively.Results: The cohort was comprised of 47 adults with SCD and 19 healthy African American controls. Sixty percent of the SCD subjects were HbSS or HbS-β-thalassemia0. Mean age (SD) of SCD cases was 35 years (±11) and 70% were female. Twenty-seven percent of SCD cases had asthma and 41% had a significant smoking history. Sixty-four percent of SCD cases had ground glass opacities on CT of the lung, 34% had bronchiectasis and 20% had evidence of pulmonary fibrosis. Compared to controls, patients with SCD had lower forced expiratory volume in 1 second (p<0.001), forced vital capacity (p<0.001), and pre- and post-bronchodilator 25-75% forced expiratory flow (FEF25-75%) (p=0.006). Fibrocyte levels also trended higher in patients with SCD compared to controls (median 1.2 x 106 vs. 8.5 x 105, p=0.07). Within patients with SCD, most fibrocytes expressed the chemokine receptor CXCR4 and smaller subsets expressed CCR2 or CCR7. Increased levels of fibrocytes in patients with SCD were associated with lower oxygen saturation (p=0.01) and higher reticulocyte counts (p=0.01). Lower oxygen saturation and higher reticulocyte counts were also associated with each other, independent of fibrocytes (p=0.007). Fibrocytes expressing CXCR4, a chemokine that mediates homing to the lungs, were associated with lower post-bronchodilator FEF25-75% (p=0.04). There was no association between fibrocyte levels and other measures of pulmonary function testing, degree of fibrosis on high-resolution CT, or abnormalities on 2-D echocardiogram or 6-minute walk.Conclusion: In adults with SCD, higher fibrocyte levels were associated with lower resting oxygen saturation and FEF25-75%, a measure of lung obstruction. Significant lung pathology was observed in a high percentage of SCD patients. The associations between fibrocyte levels, hypoxia and a measure of pulmonary dysfunction suggest that fibrocytes contribute to this lung disease. Higher reticulocyte counts in patients with increased fibrocytes may be due to the association of both reticulocyte count and fibrocyte level with hypoxia. Ongoing longitudinal studies may better define the relationship between fibrocytes and evolving lung disease. If additional evidence is found in these longitudinal studies, fibrocytes could be a therapeutic target to prevent chronic pulmonary disease in adults with SCD. DisclosuresField:NKTT: Consultancy, Research Funding. Strieter:Novartis: Employment.

Association of pro-inflammatory high-density lipoprotein cholesterol with clinical and laboratory variables in sickle cell disease

BackgroundAlthough cholesterol levels are known to be decreased in sickle cell disease (SCD), the level of pro-inflammatory high-density lipoprotein cholesterol (proHDL) and its association with clinical complications and laboratory variables has not been evaluated.Design and methodsPlasma levels of total cholesterol, high-density lipoprotein cholesterol (HDL), proHDL, and selected clinical and laboratory variables were ascertained in a cohort of SCD patients and healthy African American control subjects in this single-center, cross-sectional study.ResultsAlthough total cholesterol was significantly lower in SCD patients compared with control subjects, HDL and proHDL levels were similar in both the SCD and control groups. In univariate analyses, proHDL was correlated with echocardiography-derived tricuspid regurgitant jet velocity. ProHDL was higher in SCD patients with suspected pulmonary hypertension (PHT) compared to patients without suspected PHT. ProHDL was positively correlated with lactate dehydrogenase, total bilirubin, direct bilirubin, indirect bilirubin, prothrombin fragment 1+2, D-dimer, and thrombin–antithrombin complexes. In multivariable analyses, only higher lactate dehydrogenase and direct bilirubin levels were associated with higher levels of proHDL.ConclusionsSCD is characterized by hypocholesterolemia. Although proHDL is not increased in SCD patients compared with healthy controls, it is significantly associated with markers of liver disease. In addition, proHDL is associated with tricuspid regurgitant jet velocity and markers of coagulation, although these associations are not significant in multivariable analyses.

Lack of association of the caspase-12 long allele with community-acquired pneumonia in people of African descent.

Community-acquired pneumonia (CAP) is a common cause of sepsis. Active full-length caspase-12 (CASP12L), confined to the people of African descent, has been associated with increased susceptibility to and mortality from severe sepsis. The objective of this study was to determine whether CASP12L was a marker for susceptibility and/or severity of CAP. We examined three CAP cohorts and two control populations: 241 adult Memphis African American CAP patients, 443 pediatric African American CAP patients, 90 adult South African CAP patients, 120 Memphis healthy adult African American controls and 405 adult Chicago African American controls. Clinical outcomes including mortality, acute respiratory distress syndrome (ARDS), septic shock or severe sepsis, need for mechanical ventilation, and S. pneumoniae bacteremia. Neither in the three individual CAP cohorts nor in the combined CAP cohorts, was mortality in CASP12L carriers significantly different from that in non-CASP12L carriers. No statistically significant association between genotype and any measures of CAP severity was found in any cohort. We conclude that the functional CASP12L allele is not a marker for susceptibility and/or severity of CAP.

Microparticles As Biomarkers Of Osteonecrosis Of The Hip In Sickle Cell Disease

IntroductionSickle cell disease (SCD) is the most common cause of osteonecrosis of the femoral head (ONFH) in children. ONFH is a debilitating condition that is associated with mobility limitations, chronic pain, and an impaired quality of life. While the mechanisms that cause ONFH remain unknown, ischemia from recurrent microvascular occlusion is likely to play a role. Vascular occlusion may result directly from obstruction by sickled cells, or indirectly via complex interdependent pathways characterized by sustained endothelial activation, chronic inflammation, and coagulation. Microparticles (MP) are small, cell membrane-derived vesicles generated in response to cellular activation, injury or apoptosis. MPs have emerged as potential modulators of inflammation and thrombosis and have been found to be elevated in patients with ONFH in the general population. ObjectiveThis pilot study examined whether microparticle levels in patients with SCD who have ONFH differ from SCD patients without ONFH, as well as healthy African American (AA) controls. MethodsSubjects were recruited at their baseline status and were excluded if they had been transfused within the past 30 days, hospitalized for a vaso-occlusive pain episode, acute chest syndrome, fever or surgery within the past 30 days, or had bony lesions of the femur or hip due to causes unrelated to SCD. For MP analysis, whole blood was collected in sodium citrate tubes and centrifuged for 15 minutes at 1500 x g at 20° C to generate platelet poor plasma. Aliquots of the plasma were immediately frozen and stored at -80° C until the time of MP analysis. 300 μl samples were diluted in PBS and centrifuged at 10000 x g for 1hr and the supernatant was centrifuged at 100,000 x g for 2 hr. The pellet was re-suspended in 1 mL of PBS and subjected to nanoparticle-tracking analysis to determine concentration and size. Additional laboratory biomarkers of inflammation and coagulation, including highly-sensitive C-reactive protein (hs-CRP), von Willebrand factor antigen (vWF Ag), tissue factor (TF), and D-dimer were analyzed for differences between groups. Analysis of variance was used to compare MP and biomarker levels between the three groups. The institutional review board at Children's Hospital & Research Center Oakland approved the study protocol and written informed consent was obtained from all participants. ResultsCharacteristics of the 30 subjects enrolled are shown in Table I.Total microparticle levels in ONFH(+) patients were 2.3-fold higher than in ONFH(-) patients, and 2.5-fold higher than in AA controls (Figure 1). Mean MP levels for ONFH(+) patients, ONFH(-) patients, and AA controls were 4.55 x 1010, 1.99 x 1010, and 1.85 x 1010, respectively. Microparticle levels in ONFH(-) SCD patients did not differ from AA controls. There were no statistically significant differences in hsCRP, vWF Ag, TF, or D-dimer levels between the ONFH(-) and ONFH(+) groups. [Display omitted] [Display omitted] ConclusionsThe results of this study demonstrate significantly elevated MP levels in individuals with SCD who have ONFH. Additional studies are needed to better understand the mechanistic effects of MPs on the development of ONFH and to determine whether MP levels may be useful as a predictive biomarker for early disease detection.This publication was supported by NIH/NCRR UCSF-CTSI Grant Number UL1 RR024131. Disclosures:No relevant conflicts of interest to declare.

Vitamin D Status and Bone Mineral Density in African American Children With Crohn Disease

Vitamin D deficiency and low bone mineral density (BMD) are complications of inflammatory bowel disease. Vitamin D deficiency is more prevalent among African Americans compared with whites. There are little data comparing differences in serum 25-hydroxyvitamin D (25OHD) concentrations and BMD between African American and white children with Crohn disease (CD). We compared serum 25OHD concentrations of African American children with CD (n = 52) to white children with CD (n = 64) and healthy African American controls (n = 40). We also analyzed BMD using dual-energy x-ray absorptiometry results from our pediatric CD population. African American children with CD had lower serum 25OHD concentrations (16.1 [95% confidence interval, CI 14.5-17.9] ng/mL) than whites with CD (22.3 [95% CI 20.2-24.6] ng/mL; P < 0.001). African Americans with CD and controls exhibited similar serum 25OHD concentration (16.1 [95% CI 14.5-17.9] vs 16.3 [95% CI 14.4-18.4] ng/mL; NS). African Americans with CD exhibited no difference in serum 25OHD concentration when controlling for seasonality, disease severity, and surgical history, although serum 25OHD concentration was significantly decreased in overweight children (body mass index ≥85%, P = 0.003). Multiple regression analysis demonstrated that obese African American girls with CD had the lowest serum 25OHD concentrations (9.6 [95% CI 6.8-13.5] ng/mL). BMD was comparable between African American and white children with CD (z score -0.4 ± 0.9 vs -0.7 ± 1.2; NS). African American children with CD are more likely to have vitamin D deficiency compared with white children with CD, but have similar BMD. CD disease severity and history of surgery do not affect serum 25OHD concentrations among African American children with CD. African American children have low serum 25OHD concentrations, independent of CD, compared with white children. Future research should focus on how race affects vitamin D status and BMD in children with CD.

Vitamin D Status and Bone Mineral Density in African-American Children with Crohnʼs Disease

Purpose: Vitamin D deficiency and low bone mineral density (BMD) are complications of inflammatory bowel disease. Vitamin D deficiency is more prevalent among individuals of color, compared to Caucasians. There is little data comparing differences in serum 25-hydroxyvitamin D (25OHD) concentrations and BMD between African-American and Caucasian children with Crohn's Disease (CD). Methods: We compared serum 25OHD concentrations of African-American children with CD (n=52) to Caucasian children with CD (n=64) and healthy African-American controls (n=40). We also analyzed BMD using dual energy x-ray absorptiometry (DXA) results from our pediatric CD population. Results: African-American children with CD had lower serum 25OHD concentrations (16.1 [14.5-17.9; 95% CI] ng/mL) than Caucasians with CD (22.3 [20.2-24.6; 95% CI] ng/mL; p<0.001). African-Americans with CD and controls exhibited similar serum 25OHD concentration (16.1 [14.5-17.9, 95%CI] vs. 16.3 [14.4-18.4, 95%CI] ng/mL; NS). African-Americans with CD exhibited no difference in serum 25OHD concentration when controlling for seasonality, disease severity, and surgical history, though serum 25OHD concentration was significantly decreased in overweight children (BMI≥85%, p =0.003). Multiple regression analysis demonstrated that obese African-American females with CD had the lowest serum 25OHD concentrations (9.6 [6.8-13.5, 95%CI] ng/mL). BMD was comparable between African-American and Caucasian children with CD (Z score -0.4 ± 0.9 vs -0.7 ± 1.2; NS). Conclusion: African-American children with CD are more likely to have vitamin D deficiency compared to Caucasian with CD, but have similar BMD. CD disease severity and history of surgery do not affect serum 25OHD concentrations among African-American children with CD. African-American children have low serum 25OHD concentrations, independent of CD, compared to Caucasian children. Future research should focus on how race affects vitamin D status and BMD in children with CD.

Stroke with intracranial stenosis is associated with increased platelet activation in sickle cell anemia

Overt stroke in sickle cell anemia (SCA) is associated with intracranial stenosis and thrombus formation. Platelet activation is critical for thrombus formation. Platelet activation studies were performed in 50 subjects: 18 SCA patients with history of stroke or abnormal transcranial Doppler (TCD) and intracranial stenosis seen by magnetic resonance angiogram (MRA), 7 SCA patients with history of stroke or abnormal TCD but no intracranial stenosis, 13 SCA patients with no history of stroke or abnormal TCD, and 12 healthy African-Americans. Of the 18 patients with intracranial stenosis, 11 (61%) had evidence of the moyo-moya phenomenon on MRA. SCA children with intracranial stenosis had a significantly greater total white cell count compared to both healthy African-American controls and SCA patients in the steady-state (P < 0.001). In addition, SCA patients with history of stroke or abnormal TCD had a significantly higher platelet count compared to healthy African-American controls (P < 0.002). The percentage of platelet surface P-selectin expression was significantly greater in patients with intracranial stenosis compared to the other groups (P < 0.05), particularly in individuals that did not have the moya-moya phenomenon seen on MRA. Stroke with intracranial stenosis is associated with increased platelet activation in sickle cell anemia, and further investigation is needed on the role of anti-platelet agents in this high-risk population.

Laser Speckle Contrast Imaging Characterizes Delayed Reperfusion After Transient Brachial Artery Occlusion in Patients with Sickle Cell Diseas

AbstractAbstract 1080 Background:The pathophysiology of sickle cell disease (SCD) involves vascular complications such as stroke and pulmonary hypertension. Elevated pulmonary artery pressure estimated by cardiac ultrasound or measured by invasive right heart catheterization is associated with early mortality among patients with SCD. Peripheral vascular dysfunction has also been observed in SCD and may be easier to assess than pulmonary vascular resistance and therefore more suitable for epidemiologic or interventional studies of SCD. Three previous studies found no difference in the maximal blood flow (or percentage increase) stimulated by occlusion and reperfusion of the brachial artery, a conduit vessel, when measured by Doppler ultrasound at periodic intervals. However, a study using continuous laser Doppler measurements of cutaneous microvascular blood flow found that patients with SCD had prolonged time to maximal blood flow and prolonged time to return to baseline compared to healthy controls. In our study, we used two-dimensional laser speckle contrast imaging (LSCI) to assess the cutaneous microvascular blood flow response in adults with SCD after five minutes of brachial artery occlusion. Methods:Nine subjects with sickle cell disease were enrolled and compared against nine healthy African-American control subjects matched for age, sex, ethnicity, and body mass index. Cutaneous blood flow was directly measured using LCSI at baseline, during and after a standard brachial artery occlusion-reperfusion maneuver (inflation of an occlusive pneumatic cuff for five minutes). This stimulates a transient increase in blood flow to levels above baseline during the reperfusion phase. Blood flow data were averaged over a defined region of interest on the medial aspect of the forearm. Microvascular blood flow responsiveness was calculated as the time to maximum (time elapsed from 50% of maximum to maximum blood flow) and the time to return to baseline (time elapsed from maximum to 50% of maximum blood flow). We performed measurements on each individual on two separate days, and compared the microvascular blood flow responses between the groups using two-way ANOVA with repeated measures. Results:We enrolled nine patients with sickle cell disease (age 35 ± 8.8, BMI 23 ± 3.9, 3 men/6 women) and nine healthy controls (age 35 ± 10.7 years, BMI 25 ± 3.2, 3 men/6 women). Baseline microvascular blood flow measured in arbitrary units (AU) was greater in patients with sickle cell disease compared to healthy controls (53.1 ± 9.2 AU vs 37.2 ± 4.4 AU, p < 0.0001) but maximal microvascular blood flow was similar (121.3 ± 29.3 AU vs 124.7 ± 26.6 AU, p = 0.58). Analysis of the time from half-maximum to maximum blood flow revealed that patients with sickle cell disease take longer to reach maximum blood flow (19.1 ± 11.6 s vs 11.8 ± 1.0 s, p = 0.03) and longer to decrease from maximum to half-maximum blood flow during the recovery period (43.5 ± 13.0 s vs 28.6 ± 10.4 s, p = 0.002). Conclusion:Compared to healthy individuals, patients with SCD have greater baseline microvascular blood flow but similar maximal blood flow during reperfusion. However, patients with SCD differ significantly from healthy control subjects in the time required to reach maximal blood flow and the time required to return to baseline, both of which are prolonged in patients with SCD. This may reflect delayed or impaired endothelial responses to shear stress and/or greater viscosity of blood. Time to maximal blood flow might represent a useful physiological biomarker as a proxy for clinical severity of sickle cell anemia, and a potential surrogate marker in early phase clinical trials. This technique merits additional characterization and validation. Disclosures:No relevant conflicts of interest to declare.

Abstract A58: Role of insulin-like growth factor binding protein acid labile complex in ER-PR- Her2+ breast cancer in African American women.

Abstract The emergence of the obesity epidemic worldwide has been associated with increases in breast cancer and type 2 diabetes. Symptoms associated with obesity collectively known as metabolic syndrome have been associated with triple negative breast tumors that are common among premenopausal women, especially those of African American (AA) descent. The insulin-leptin adiponectin axis has been implicated in these breast tumors that are insensitive to estrogen. It is suggested that insulin, insulin like growth factors and epidermal growth factors mediate the interactions between these hormones. Previous studies have shown that insulin like growth factor 2 (IGF-2) synergistically cross-talks with estrogen receptor (ER) alpha and ER-beta to promote estrogen independent breast cancer progression. This suggests that IGF-2 can activate insulin like growth factor I (IGF-1) receptor and insulin receptor to activate both ER alpha and ER beta in breast cancer cells leading to proliferation and tumorigenesis. The purpose of this study was to find the the role of insulin-like growth factor binding protein acid labile complex (IGFBP-ALS) identified in our previous serum proteomic pilot study that included six AA breast cancer women and six healthy AA controls. Methods: The serum samples were processed on IgY12 (Beckman) antibody column to remove the top 12 proteins. The flow through fraction was digested using trypsin for LC/MS analysis. The protein digest serum samples were analyzed in triplicate on a high performance LTQFT (Thermo Electron) mass spectrometer coupled to an online Surveyor LC system equipped with an autosampler. Samples were loaded onto a trap column using a sample pump. An MS pump was used for eluting the peptides onto an analytical column for further separation and online nano-ESI LC/MS/MS analysis. The raw MS data files were imported into DeCyderMS (GE Healthcare) module and data were processed for peptide/protein expression analysis. Results: DeCyderMS analysis revealed significant differences in the expression of 215 peptides between the two groups (t-test: &amp;lt; 0.05; ave fold ratio: &amp;lt;0.5 or &amp;gt;2). Most of these peptides were mapped to 28 proteins in the Swiss-Prot database. DecyderMS analyses on all the replicates from each sample are underway to identify the peptide pattern differences between the healthy and cancer samples. Among other differentially expressed proteins IGFBP-ALS was significantly low in sera from African American women with breast cancer with tumors possessing the ER-PR-Her2+receptor status. In a previous study, 60% of the women from the same cohort experienced metabolic syndrome. Conclusions: It is suggested that IGFBP-ALS is necessary for the binding of IGF-1 or IGF-2 to the plasma IGF protein BP-53. Low levels of IGFBP-ALS subunit in the sera of ER-PR-HER2+ AA cancer patients could serve as biomarker for early-stage, breast cancer with aggressive features. Additionally this protein could reveal an association between obesity and breast cancer. Efforts are currently underway to validate this biomarker to gain insight into the etiology of aggressive breast tumors in AA women. Funded by The Susan G. Komen For the Cure Breast Cancer Foundation. Citation Format: Padma Uppala. Role of insulin-like growth factor binding protein acid labile complex in ER-PR- Her2+ breast cancer in African American women. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A58.

Patients with Sickle Cell Disease Have Increased Sensitivity to Cold and Heat Stimuli, 2

Abstract 2116Sickle Cell Disease (SCD) pain is associated with colder temperatures, touch, and increased wind speed and barometric pressure. The specific array of associated factors suggests hypersensitivity to tactile stimuli, a characteristic of neuropathic pain. Sickle mice exhibit hypersensitivity at baseline compared to controls to cold, heat, and mechanical stimuli via a TRPV1 mediated pathway. However, it is not known whether humans experience this same hypersensitivity. Thus, the objective of this study was to quantify sensitivity differences to thermal (heat, cold) and mechanical stimuli between SCD patients and healthy African American controls. We hypothesized SCD patients will exhibit hypersensitivity to thermal and mechanical stimuli compared to controls and this hypersensitivity will worsen with age and frequency of pain.We conducted a cross-sectional study of SCD patients in baseline health and race-matched controls age ≥ 7 yrs. Our primary outcome was detection of hypersensitivity to thermal and mechanical stimuli. We excluded those with a pain phenotype other than SCD, overt stroke, analgesics within 24 hrs of testing, or acute SCD pain event within 2 weeks of testing. Subjects underwent quantitative sensory testing (QST) to thermal and mechanical stimuli. QST evaluates the somatosensory system detecting sensory loss (hyposensitivity) or gain (hypersensitivity). Thermal stimulation was performed with a Thermal Sensory Analyzer (Medoc;Israel), an FDA approved computer-assisted device that delivers cold and warm stimuli via a thermode attached to the skin (baseline temperature, 32°C; stimulus range, 0–50°C). Mechanical testing was performed using graded vonFrey monofilaments (force range 0.255 mN to 1078.731 mN). Testing was done on the thenar eminence of the non-dominant hand. Primary outcomes included: 1) Cold Pain Threshold (°C), 2) Heat Pain Threshold (°C), 3) Mechanical Pain Threshold (mN) as reported by “method of limits” where subjects pushed a button (thermal) or spoke (mechanical) when the progressive stimulus was painful. The final outcome was the computed mean of 3 tests (thermal) and 5 tests (mechanical).Independent samples t-tests were used to compare outcomes between SCD patients and controls. Linear regression was used to evaluate the impact of age and gender on pain thresholds in both groups and the impact of lifetime history of pain, defined as total number of emergency department visits or hospitalizations for pain, on pain thresholds in SCD patients.55 SCD patients and 57 controls were recruited (Jan 2010-June 2011). There were no differences in mean age (15.4 yrs vs.16.3 yrs; p=0.59, t-test) or gender (SCD=60% female vs. Controls=56% female; p=0.70, Pearson Chi-Square). SCD genotypes were 67% (n=37) HbSS, 18% (n=10) HbSC, 11% (n=6), HbSβ+thal, and 4% (n=2) other. SCD patients had significantly lower cold pain thresholds (p=0.008) and heat pain thresholds (p=0.04) compared to controls (Table 1). There were no differences in mechanical pain thresholds (p=0.38) (Table 1). Older age was associated with lower cold pain thresholds (parameter estimate=0.19°C; p=0.05), lower heat pain thresholds (parameter estimate=0.13°C; p=0.0069), and lower mechanical pain thresholds (parameter estimate=0.11mN; p=0.02) in both groups. Gender had no effect on the outcomes (cold pain threshold, p=0.15; heat pain threshold, p=0.07; mechanical pain threshold, p=0.29). Total number of lifetime SCD pain events had no effect on the outcomes (cold pain threshold, p=0.91; heat pain threshold, p=0.65, mechanical pain threshold, p=0.77).SCD patients in baseline health experience increased sensitivity to cold and heat stimuli compared to race-matched controls and this sensitivity worsens with older age. These findings suggest peripheral sensitization may exist in SCD. Further research into how cold and heat sensing receptors and pathways contribute to SCD pain is warranted. Ultimately, this may lead to the development of novel therapeutics targeted to the specific underlying neurobiology of SCD pain that aids in the treatment or prevention of SCD pain.Table 1Pain Thresholds of SCD Patients and Healthy Controls.OutcomeSCD Patients (Mean ± SD)Controls (Mean ± SD)P-valueCold Pain Threshold (°C)18.5 (7.7)14.1 (9.4)0.008Heat Pain Threshold (°C)42.5 (4.4)44.3 (4.6)0.04Mechanical Pain Threshold (mN)303.9 (409.6)375.6 (451.2)0.38 Disclosures:No relevant conflicts of interest to declare.

Significance of Plasma C-peptide in Obese African American Adolescents

C-peptide blood levels can indicate whether or not a person is producing insulin and roughly how much. C-peptide is secreted as a byproduct of the biosynthesis of insulin from proinsulin. C-peptide has proposed biological activity and a well-established diagnostic value. The significance of C-peptide concentration in the plasma and urine in the pediatric population needs further delineation. To determine the significance of plasma C-peptide in obese African American adolescents with mild insulin resistance but no evidence of diabetes. This study included 19 African American adolescents with body mass index (BMI) in at least the 85th percentile evaluated with anthropometric measurements, Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) score, and oral glucose tolerance test (OGTT), and 24-hour urine collections. The study also included an age-matched control group of 15 healthy African American adolescent controls and were not subjected for OGTT. The correlation among BMI, fasting plasma C-peptide concentrations, and 24-hour-urine C-peptide concentrations was calculated. T Tests were conducted to compare plasma C-peptide and 24-hour-urine C-peptide concentrations for the test group and controls. Mean HOMA score (3.96 +/- 1.84) signified mild insulin resistance among the adolescent test group. The test subjects exhibited adequate glucose tolerance (glucose range, 89.4-122.5 mg/dL) during the OGTT. A significant positive relationship was observed between BMI and fasting plasma C-peptide concentration in the control group (r = 0.537) but not the test group (r = 0.335). An insignificant positive relationship was exhibited between BMI and 24-hour-urine C-peptide concentration in the test group (r = 0.150) and controls (r = 0.254). The positive relationship among BMI, plasma C-peptide, and urine C-peptide is worth further evaluation in studies conducting multiple rounds of OGTT with a larger sample of pediatric subjects. The potential diagnostic value of C-peptide may facilitate early detection of insulin resistance in the pediatric population.

Novel p.Ile151Val mutation in VCP in a patient of African American descent with sporadic ALS

The valosin containing protein (VCP) is a member of the AAA-ATPase family, a group of enzymatic molecular chaperones that have been associated with a range of cellular processes including ubiquitin-proteasome mediated degradation, membrane fusion, apoptosis, cell-cycle control, and autophagy.1 Mutations in VCP were first identified to cause familial inclusion body myopathy with early-onset Paget disease and frontotemporal dementia2 (IBMPFD) and more recently were found to be implicated in familial amyotrophic lateral sclerosis (ALS).3 It was suggested that VCP mutations may account for 1%–2% of familial ALS cases.3 Whether VCP mutations also contribute to sporadic ALS (SALS), however, has not yet been studied. Here, we report the identification of a novel p.Ile151Val mutation in VCP in a patient of African American descent with SALS. ### Case report. In the course of screening patients with ALS ascertained by the ALS Center at Mayo Clinic Florida (MCF) for mutations in the known ALS genes ( SOD1 , TARDBP , FUS , OPTN , and VCP ), we identified an African American patient with the c.451A>G mutation in exon 5 of VCP predicted to result in the p.Ile151Val substitution. Mutations were excluded in all other exons and genes analyzed in this patient. The VCP p.Ile151Val mutation was not previously reported in dbSNP or the 1000 Genomes databases and genotyping using a custom-designed ABI Taqman assay excluded this mutation from 407 healthy African American controls obtained from MCF (n = 317) and the Coriell Institute for Medical Research (n …

Most common single‐nucleotide polymorphisms associated with rheumatoid arthritis in persons of European ancestry confer risk of rheumatoid arthritis in African Americans

Large-scale genetic association studies have identified >20 rheumatoid arthritis (RA) risk alleles among individuals of European ancestry. The influence of these risk alleles has not been comprehensively studied in African Americans. We therefore sought to examine whether these validated RA risk alleles are associated with RA risk in an African American population. Twenty-seven candidate single-nucleotide polymorphisms (SNPs) were genotyped in 556 autoantibody-positive African Americans with RA and 791 healthy African American control subjects. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for each SNP were compared with previously published ORs for RA patients of European ancestry. We then calculated a composite genetic risk score (GRS) for each individual based on the sum of all risk alleles. Overlap of the ORs and 95% CIs between the European and African American populations was observed for 24 of the 27 candidate SNPs. Conversely, 3 of the 27 SNPs (CCR6 rs3093023, TAGAP rs394581, and TNFAIP3 rs6920220) demonstrated ORs in the opposite direction from those reported for RA patients of European ancestry. The GRS analysis indicated a small but highly significant probability that African American patients relative to control subjects were enriched for the risk alleles validated in European RA patients (P = 0.00005). The majority of RA risk alleles previously validated for RA patients of European ancestry showed similar ORs in our population of African Americans with RA. Furthermore, the aggregate GRS supports the hypothesis that these SNPs are risk alleles for RA in the African American population. Future large-scale genetic studies are needed to validate these risk alleles and identify novel RA risk alleles in African Americans.