Sickle Cell Trait Research Articles

Impact of haemoglobin variants on the diagnostic sensitivity of glycated haemoglobin (HbA1c) assay methodologies in sub-Saharan Africa: a laboratory-based method validation study.

the utility of glycated haemoglobin (HbA1c) for the diagnosis and monitoring of diabetes in sub-Saharan Africa is uncertain due to limited data on the performance of the available HbA1c assay methods in this population, which has a high prevalence of haemoglobin variants. We aimed to compare the diagnostic accuracy of the major HbA1c methodologies (Boronate Affinity, Capillary Electrophoresis, High Performance Liquid Chromatography, Immunoassay) in an African population, and assess the impact of the common haemoglobin variant HbAS (sickle cell trait). whole blood samples were obtained from 182 individuals living with type 2 diabetes in Uganda. HbA1c values for each method were compared to average glucose measured over 14 days by continuous glucose monitoring (CGM). To determine concordance, the three HbA1c assay methods were compared to the capillary electrophoresis method. there was a strong correlation between CGM average glucose levels and all four HbA1c methodologies (r=0.81-0.89) which did not differ in those with and without HbAS (present in 37/182 participants). The presence of HbAS did not alter the relationship between HbA1c and CGM glucose for any assay (p for interaction >0.2 for all methods). Diagnostic accuracy for CGM average glucose thresholds of 7 and 10mmol/L was similar across methods (area under the receiver operating characteristic curve 0.80-0.84 and 0.76-0.84 respectively). The maximum bias between the HbA1c assay methodologies was 2 mmol/mol (2.07%). all major HbA1c technologies offer accurate and comparable HbA1c measurement even in this population with high prevalence of haemoglobin variants.

Comparative study of sickling test, solubility test, and hemoglobin electrophoresis in sickle cell anemia

Abstract Background: Madhya Pradesh, a state in India, bears the highest number of sickle cell anemia (SCA) cases, particularly among its tribal communities. The diagnosis of suspected SCA cases involves utilizing several methods. The sickling test operates on the principle of hemoglobin S (HbS) polymerization upon deoxygenation. By contrast, the solubility test involves the reduction of HbS using sodium hydrosulfite, followed by precipitation of lysed red blood cells. Hemoglobin (Hb) electrophoresis identifies Hb variants based on their migration in an electric field. Our objective was to assess the efficacy of sickling and solubility tests as screening tools for detecting SCA, comparing them against capillary Hb electrophoresis, which is considered the gold standard. Materials and Methods: All individuals suspected of having SCA between 2022 and 2023 were enrolled in the study. Clinical information, peripheral blood smear analysis, sickling test, solubility test, and capillary Hb electrophoresis were conducted, and the results were compared. Results: Of 250 cases assessed, Hb electrophoresis identified 225 cases of SCA, resulting in a sickle cell disease to sickle cell trait (SCT) ratio of 1:1.36 and a male-to-female ratio of 1:1.33. The highest number of cases were observed in the age group from 21 to 30 years. Generalized weakness (77%) and abdominal pain (52%) were the most frequently reported symptoms. The sickling test demonstrated a sensitivity, specificity, and diagnostic accuracy of 91.5%, 72%, and 89%, respectively, compared with Hb electrophoresis. The solubility test yielded values of 76.5%, 68%, and 75% for sensitivity, specificity, and diagnostic accuracy, while peripheral smear analysis showed 36%, 25%, and 42%, respectively. Conclusion: The sickling test displayed superior sensitivity and diagnostic accuracy compared with the solubility test, with no significant disparity in specificity between these two methods. Notably, the solubility test exhibited a higher incidence of false-negative results for SCT. Therefore, the sickling test is the preferred screening method for SCA.

Association of Sickle Cell Disease, Malaria and HIV in Multi Drug Resistant Invasive Non-typhoidal Salmonella Isolated from Outpatient and Hospitalised Children Below 16 Years in Informal Settlements in Nairobi County, Kenya.

Invasive non-typhoidal Salmonella (iNTS) disease continues to be a major public health problem, especially in sub-Saharan Africa (SSA), where incidence rates are 227 cases [range 152-341] per 100,000 populations. Populations at risk of iNTS include adults with human immunodeficiency virus (HIV) infection, malnourished children, and those with recent malaria or sickle-cell anaemia (SCA). In Kenya, iNTS disease is particularly a major challenge in poor informal settlements, with infants and young children less than 5 years of age being the most affected. Our study aimed to investigate the association between sickle cell disease, malaria, and HIV in multi-drug-resistant invasive non-typhoidal Salmonella from outpatient and hospitalised children ≤16 years in informal settlements in Nairobi County, Kenya. This study recruited 16,679 children aged ≤16 years who presented with salmonellosis symptoms for a period of 6 years (2013-2018). The patients were age-matched with controls (asymptomatic individuals). The study was conducted at 3 outpatient sites and 1 inpatient site; the outpatient sites were all located within the Mukuru informal settlement. The inpatient site was Mbagathi district hospital, which serves patients residing in Kibera informal settlement. Blood and stool samples from children with fever ≥38°C and/or diarrhea and stool samples alone from controls were collected for processing for the presence of iNTS using basic microbiology procedures including culture, serology, and Kirby Bauer disc diffusion for sensitivity testing. Dry blood spots were also taken and processed for sickle cell protein markers using high-performance liquid chromatography (HPLC). HIV and malaria tests were also conducted using rapid tests, respectively. From the total of 22,246 blood and stool samples tested, 741 (3.3%) tested positive for Salmonella species. A total of 338 (45.6%) iNTS were isolated across all 4 sites; these consisted of 158 (21.3%) Salmonella Enteritidis and 180 (24.3%) Salmonella Typhimurium. The most common resistance phenotype was against ampicillin, chloramphenicol, and sulfamethoxazole trimethoprim. A total of 118 (34.9%) isolates were multidrug-resistant (MDR). Out of 2,684 dry blood samples subjected to HPLC for investigation of sickle cell disease traits, 1820 (67.8%) had normal haemoglobin (Hb AA/Hb AF); 162/2684 (6%) tested positive for sickle cell traits (Hb AS/Hb AFS). Some patients positive for iNTS were also found to have other co-morbidities; 4 (0.1%) tested positive for sickle cell disease (Hb FS), malaria, and HIV 8 (2.4%) and 5 (1.5%), respectively. The high prevalence of MDR iNTS isolates and emerging resistance to third-generation cephalosporins is of great concern, as they are the recommended drugs for the management of iNTS in our settings. Sickle cell disease, malaria, and HIV were all not major factors associated with iNTS disease among children in Mukuru and Kibera informal settlements.

Promoting Sickle Cell Trait Awareness and Education: A Typology of Interventions in the United States to Inform Ongoing Efforts to Patients and Providers

Promoting Sickle Cell Trait Awareness and Education: A Typology of Interventions in the United States to Inform Ongoing Efforts to Patients and Providers

A Rare Case of Compound Heterozygous Sickle Cell Beta Thalassaemia with High HbF and Normal HbA2 Levels Detected on HPLC

Compound heterozygous Sickle Haemoglobin (HbS) beta (β) thalassaemia arises from the mutations associated with sickle cell and β thalassaemia and significantly affects populations in low income countries like India. Elevated levels of Haemoglobin A2 (HbA2) represent the primary indicator for identifying carriers of β thalassaemia. However, it’s worth noting that sometimes, High Performance Liquid Chromatography (HPLC) encounters challenges in confirming a final diagnosis when levels of HbA2 and HbS fall outside the diagnostic range. A nine-year-old male and his sister 11-year-old female patient presented with high-grade fever and jaundice since two weeks. Following admission, Complete Blood Count (CBC) and HPLC of both children were done. Hb of male and female child revealed 1.8 g/dL and 1.5 g/dL, respectively. HPLC of male child revealed Haemoglobin F (HbF) 27.4%, HbS 56.3%, HbA2 3.8% and of female child revealed HbF 39.2%, HbS 43.5%, HbA2 3%. HPLC reports of both children were suggestive of differential of compound heterozygous HbS β thalassaemia and HbS homozygous. Later, HPLC of their parents was also done. HPLC of father was suggestive of thalassaemia trait and of mother suggestive of sickle cell trait, following which final diagnosis of both children was given as compound heterozygous HbS β thalassaemia. Diagnosing these compound heterozygous haemoglobinopathies can be challenging. As their is resemblance in clinicopathological features of sickle cell anaemia and β thalassaemia disorders, it is important to carefully differentiate between them although prognosis is better than thalassaemia major or sickle cell anaemia.

Sickle cell disease in the Zanzibar Archipelago, the Republic of Tanzania.

Sickle cell disease (SCD) is one of the most severe haemoglobinopathies, a group of blood disorders, typically inherited. The condition affects over 7.7 million people globally and results in more than 370,000 deaths per year. The highest morbidity and mortality rates are seen in Africa and most children with SCD are born in Tanzania. The available literature on SCD morbidity in Tanzania focus primarily on the residents of the mainland, while there is little data available on SCD morbidity among residents of the Tanzanian islands in the Indian Ocean. The aim of the present study was to confirm the presence of sickle cell disease among residents of the Zanzibar Archipelago. The study group consisted of 27 people, residents of Pemba Island in the Zanzibar Archipelago, aged between 2 months and 26 years old, whose at least one parent has been diagnosed with sickle cell anaemia. Blood samples collected from the study participants were tested using HemoTypeSCTM, a rapid, point-of-care diagnostic test. The tests were performed at the Amal Hospital (Chake Chake town, Pemba Island) in June 2023. Sickle cell disease was diagnosed in 11 study subjects (40.7%); their haemoglobin concentration ranged between 6.6 and 8.5 g/dL. The presence of the sickle cell trait (HbAS phenotype) was confirmed in 14 patients (51.9%). Only two of the tested patients had normal haemoglobin phenotype. The results of the present study support the necessity to introduce large-scale population- -based screening for SCD in the Zanzibar Archipelago, especially in infants whose family members have sickle cell anaemia. The introduction of such a programme will help monitor the number of new SCD cases in the region and may potentially reduce infant mortality due to SCD as well as minimize complications from SCD in older children through the adoption of effective disease prevention measures.

Sickle Cell Anemia Screening in Newborns and Analysis of Haplotypes in Patients from Santiago Island, Cape Verde.

Sickle cell anemia (SCA) results from a mutation in the β-globin gene, leading to the production of mutant hemoglobin, known as hemoglobin S (HbS). Despite being a genetic disorder, the phenotype of SCA can be influenced by the level of fetal hemoglobin (HbF), which is associated with beta S-globin haplotypes. In this study, we conducted newborn screening (NBS) using samples collected from umbilical cord blood in two hospitals on Santiago Island, Cape Verde. In newborns, HbS was detected using high-performance liquid chromatography (HPLC) on dried blood spot, with confirmation through polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). In addition, we assessed the hematological and clinical characteristics of a second population group consisting of patients diagnosed with SCA. Haplotype determination was performed on both newborns with HbS and patients with SCA. Beta S-globin haplotypes were determined using PCR-RFLP. Hematological values were analyzed using standard methods. Out of 346 newborns, 21 (6%) were carriers of the sickle cell trait (HbAS) while none were identified as homozygous for sickle cell disease (HbSS). Among both groups of individuals, four haplotypes were identified: Senegal, Arabi-Indian, Bantu, and Benin. The Senegal haplotype was the most prevalent, possibly reflecting the ethnic origin of the mutations observed. Hematological values did not differ significantly among haplotypes. However, higher levels of HbF were associated with better hematological values. These findings suggest a positive impact of elevated HbF levels on reducing the severity of SCA. Finally, we demonstrated how the combination of technics, HPLC and molecular analysis, provided a consistent and reproducible results that can be used for NBS for SCA.

Winning the fight against sickle cell disease in Africa: The need to redefine premarital sickle cell trait screening to promote awareness.

Winning the fight against sickle cell disease in Africa: The need to redefine premarital sickle cell trait screening to promote awareness.

VASO-OCCLUSIVE CRISIS IN A PATIENT WITH SICKLE CELL TRAIT

Sickle cell trait occurs as a result of inheritance of a normal haemoglobin gene (HbA) from one parent and a mutated sickle haemoglobin (HbS) gene from another. Unlike the sickle cell disease, it is considered a benign condition in itself. However, major vaso-occlusive complications have been reported in association with Sickle cell trait, the acute chest syndrome being the most important one. We report the case details of a 32 years male who presented with features of acute chest syndrome and was later found to have sickle cell trait.

Do Blood group and Sickle cell trait protect against placental malaria?

Blood group O is reported to confer some degree of protection from severe malaria in endemic setting. This protection is believed to be due to reduced and smaller rosette formation in people of blood group O which can easily be cleared by the host immune system. Also, sickle cell trait (HbAS) is reported to disrupt the adhesion of infected erythrocytes to microvascular endothelial walls, which could protect pregnant women from placental malaria. We determined the association between HbAS and ABO blood group, and placental malaria amongst pregnant women of all parities. The study enrolled 221 pregnant women. Peripheral blood samples were taken for malaria smears, ABO blood grouping and haemoglobin (Hb) electrophoresis. A struc‑ tured questionnaire was used to age, bed net usage, and the number of Sulphadoxine‑pyrimethamine (SP) doses taken by a pregnant woman. Two hundred and twenty‑one (221) pregnant women were enrolled and out of this number, 110 (49.8%) were primiparae and 111 (50.2%) multiparae, with a mean age of 23.7±5.2. Placental malaria (PM) prevalence by PCR detection was 19.4% (43/221). Of those who were malaria positive 58.1% (25/43) were primiparae. Primiparae who are of blood group O were more susceptible to PM [P=0.04, (OR); 2.85, 95% (Cl), 1.12‑9.01]. But sickle cell trait did not reduce the prevalence of PM [P=0.84 (OR); 0.92, 95% (Cl), 0.43‑1.99]. Non‑blood group O primiparae women were protected against placental malaria. This could be why some primiparae women are protected from PM, just like multiparae women.

Do Blood group and Sickle cell trait protect against placental malaria?

Blood group O is reported to confer some degree of protection from severe malaria in endemic setting. This protection is believed to be due to reduced and smaller rosette formation in people of blood group O which can easily be cleared by the host immune system. Also, sickle cell trait (HbAS) is reported to disrupt the adhesion of infected erythrocytes to microvascular endothelial walls, which could protect pregnant women from placental malaria. We determined the association between HbAS and ABO blood group, and placental malaria amongst pregnant women of all parities. The study enrolled 221 pregnant women. Peripheral blood samples were taken for malaria smears, ABO blood grouping and haemoglobin (Hb) electrophoresis. A structured questionnaire was used to age, bed net usage, and the number of Sulphadoxine-pyrimethamine (SP) doses taken by a pregnant woman. Two hundred and twenty-one (221) pregnant women were enrolled and out of this number, 110 (49.8%) were primiparae and 111 (50.2%) multiparae, with a mean age of 23.7±5.2. Placental malaria (PM) prevalence by PCR detection was 19.4% (43/221). Of those who were malaria positive 58.1% (25/43) were primiparae. Primiparae who are of blood group O were more susceptible to PM [P=0.04, (OR); 2.85, 95% (Cl), 1.12-9.01]. But sickle cell trait did not reduce the prevalence of PM [P=0.84 (OR); 0.92, 95% (Cl), 0.43-1.99]. Non-blood group O primiparae women were protected against placental malaria. This could be why some primiparae women are protected from PM, just like multiparae women.

Differential sensitivity to hypoxia enables shape-based classification of sickle cell disease and trait blood samples at point of care.

Red blood cells (RBCs) become sickle-shaped and stiff under hypoxia as a consequence of hemoglobin (Hb) polymerization in sickle cell anemia. Distinguishing between sickle cell disease and trait is crucial during the diagnosis of sickle cell disease. While genetic analysis or high-performance liquid chromatography (HPLC) can accurately differentiate between these two genotypes, these tests are unsuitable for field use. Here, we report a novel microscopy-based diagnostic test called ShapeDx™ to distinguish between disease and trait blood in less than 1 h. This is achieved by mixing an unknown blood sample with low and high concentrations of a chemical oxygen scavenger and thereby subjecting the blood to slow and fast hypoxia, respectively. The different rates of Hb polymerization resulting from slow and fast hypoxia lead to two distinct RBC shape distributions in the same blood sample, which allows us to identify it as healthy, trait, or disease. The controlled hypoxic environment necessary for differential Hb polymerization is generated using an imaging microchamber, which also reduces the sickling time of trait blood from several hours to just 30 min. In a single-blinded proof-of-concept study conducted on a small cohort of clinical samples, the results of the ShapeDx™ test were 100% concordant with HPLC results. Additionally, our field studies have demonstrated that ShapeDx™ is the first reported microscopy test capable of distinguishing between sickle cell disease and trait samples in resource-limited settings with the same accuracy as a gold standard test.

Iron profile in sickle cell heterozygous children: A case control study

Iron deficiency is the most common nutritional deficiency worldwide & it is an important public health problem in developing countries like India. Normally chronic hemolytic anemia are iron loaded because of excessive breakdown of RBC & increased frequency of blood transfusion, but there is small or no transfusion on sickle cell trait. This study has been done to see the iron profile among sickle cell trait children in western Odisha. To determine the iron profile in children with sickle cell trait & normal healthy controls & compare them. This was a case control study that has been conducted over a period of two years. A total of 202 subjects were included in the study; 102 of them were sickle cell heterozygous & 100 of them were normal healthy controls. Iron deficiency anemia among sickle cell trait & healthy controls were screened using various clinical & laboratory criteria. A total of 202(n=202) study populations comprising of 102 sickle cell trait & 100 normal study populations were screened. A little female preponderance (n=109, 54%) was observed in this study. Abnormalities in blood parameters like MCV, MCH, MCHC, Serum ferritin were found to be statistically significant (p<0.005). Others clinical features like pallor, picophagia, sore tongue, fatigue was also found to be statistically significant (p<0.005). Out of 202 study populations 17 out of 102 sickle cell trait cases & 16 out of 100 normal controls were found to have Iron deficiency anemia. In this study it showed that there were many sickle cell trait patients who were actually iron deficient. These patients should be screened carefully to look for Iron deficiency anemia. Clinical parameters like pallor, fatigue, picophagia, sore tongue & others laboratories parameters like MCV, MCH, MCHC, Serum ferritin were helpful in diagnosing Iron deficiency anemia.

Incidence Trends of Inherited Anemias at the Global, Regional, and National Levels Over Three Decades.

Inherited anemia continues to pose a significant public health concern on a global scale, owing to its extensive geographical prevalence, substantial patient population, and profound ramifications. Here, we investigated detailed information on inherited anemias (including thalassemias, thalassemiastrait, sickle cell disease, sickle cell trait, G6PD deficiency, and G6PD trait) for the period 1990-2019 from the Global Burden of Disease study. Over the course of three decades, there has been a persistent rise in the incidence of inherited anemias worldwide, culminating in a total of 44,896,026 incident cases in 2019. However, the prevalence of inherited anemias has exhibited a consistent downward trend over successive years. Significantly, these inherited anemias primarily impact females, exhibiting a male-to-female ratio of 1:1.88. Among males, the most prevalent inherited anemia is G6PD deficiency, whereas G6PD trait prevails among females. The incidence rates of inherited anemias and their temporal trend exhibited significant variations across different regions, with Central Sub-Saharan Africa displaying the highest incidence rates and Central Latin America experiencing the most substantial decline. The findings of this study suggest a significant correlation between the Socio-Demographic index (SDI) and incidence rates of inherited anemias, particularly in regions with lower SDI levels such as Africa and South Asia. These results contribute valuable insights for the analysis of global trends in the burden of inherited anemias.

COVID-19 outcomes in patients with sickle cell disease and sickle cell trait compared with individuals without sickle cell disease or trait: a systematic review and meta-analysis

Clinical manifestations and severity of SARS-CoV-2 infection in individuals with sickle cell disease (SCD) and sickle cell trait (SCT) are not well understood yet. We performed a systematic review and meta-analysis to assess COVID-19 outcomes in individuals with SCD or SCT compared to individuals without sickle cell disease or trait. An electronic search on PubMed, Embase, and Cochrane Library was performed on August 3, 2023. Two authors (IFM and ISP) independently screened (IFM and ISP) and extracted data (IFM and ILC) from included studies. Main exclusion criterion was the absence of the non-SCD/SCT group. Exposure effects for binary endpoints were compared using pooled odds ratio (OR) with 95% confidence intervals (CI). I2 statistics was used to assess the heterogeneity and DerSimonian and Laird random-effects models were applied for all analyses to minimize the impact of differences in methods and outcomes definitions between studies. The overall quality of evidence was assessed using the GRADE system. Review Manager 5.4 and R software (v4.2.2) were used for statistical analyses. Registered with PROSPERO, CRD42022366015. Overall, 22 studies were included, with a total of 1892 individuals with SCD, 8677 individuals with SCT, and 1,653,369 individuals without SCD/SCT. No difference in all-cause mortality was seen between SCD/SCT and non-SCD/SCT (OR 1.18; 95% CI 0.78-1.77; p=0.429; I2=82%). When considering only studies adjusted for confounders (8 studies), patients with SCD/SCT were shown to be at increased risk of death (OR 1.86; 95% CI 1.30-2.66; p=0.0007; I2=34%). No significant difference was seen between individuals with SCD and SCT (p=0.863). The adjusted for confounders analysis for hospitalisation revealed higher rates for the SCD (OR 5.44; 95% CI 1.55-19.13; p=0.008; I2=97%) and the SCT groups (OR 1.31; 95% CI 1.10-1.55; p=0.002; I2=0) compared to the non-SCD/SCT population. Moreover, it was significantly higher for the SCD group (test for subgroup difference; p=0.028). Our findings suggest that patients with SCD or SCT may present with a higher mortality and hospitalisation rates due to COVID-19 infection. None.

APOEe4*TREM2 and sickle cell trait in a late onset Alzheimer’s disease mouse model

AbstractBackgroundAlzheimer’s disease (AD) is a neurodegenerative disease associated with neuroinflammation, dysregulated neurovascular coupling, abnormal neuroplasticity, and neuropathological makers, including tau and β‐amyloid deposition. Advancing age is the greatest risk factor, and apolipoprotein E (APOE) e4 and triggering receptor expressed on myeloid cells 2 (TREM2) are genetic risk factors for late‐onset AD, which comprises >95% of all AD cases. Sickle cell trait (SCT) refers to the heterozygous inheritance of the sickle cell hemoglobin mutation. Studies from our laboratory and others show that SCT is associated with increased risk of microvascular complications and peripheral inflammation. Given the role of cerebral small vessel disease and inflammation in the pathogenesis of AD, we hypothesized that SCT may interact with late‐onset AD gene variants, resulting in earlier development of cognitive impairments, possibly via promoting neuroinflammation.MethodTo test our hypothesis, 10‐12 weeks old mice carrying APOE e4*TREM2 combined late‐onset AD genes were transplanted with bone marrow from humanized Townes mice with SCT (AS) or normal (AA) hemoglobin, following irradiation. Using a longitudinal cross‐sectional design, 3 cohorts were evaluated at 8, 12, and 18 months for presence of cognitive deficits using rodent behavioral testing. Mice were sacrificed immediately following behavioral testing, and brain tissue was evaluated using immunohistochemistry and Golgi‐Cox impregnation histology.ResultBehavioral testing suggested only age‐related cognitive impairments. There were no significant differences in neuroinflammation at any age between AS and AA mice in the hippocampus or corpus callosum and external capsule. Within genotypes, there was an age dependent increase in neuroinflammation, between 8 and 12 months in the hippocampus (p < 0.0001, p = 0.0002) and 12 versus 18 months in white matter tracts (p < 0.0001, p < 0.0001). There were no significant differences in the dendritic spine density or the proportion of immature spines between AS and AA mice. However, within genotypes there was significant differences between 12 and 18 months (p < 0.0001, p < 0.0001), with 18 months having lower spine density and higher proportion of immature spines.ConclusionAddition of SCT to a background of APOE e4*TREM2 did not result in earlier onset of cognitive impairment or more severe neuroinflammation.

Rapid haemoglobin A and S quantification using Tosoh HLC-723G8 in variant mode for patients with sickle cell disease.

The management of life-threatening complications in patients with sickle cell disease (SCD) requires an accurate and reproducible quantification of haemoglobin A (HbA) and S (HbS) with a short turnaround time and 24-7 availability. We propose a novel method for quantifying HbA and HbS using the glycated haemoglobin (HbA1c) assay on a Tosoh HLC-723G8 (G8) analyser in variant mode. HbA and HbS results obtained using our method highly correlated with results obtained using a reference method (r > 0.99 for 124 samples of patients with SCD or sickle cell trait). Our method met laboratory requirements for linearity (coefficient of variation [CV] and bias <5%), between-run and within-run reproducibility (CV <10%) and carryover (<0.5%) over the range of HbS and HbA values expected in a therapeutic context. Using the G8 analyser in variant mode is viable for monitoring HbA and HbS concentrations in dire situations. This method is easy to use, quick (1.6min per sample), and automatable and produces highly reproducible results without significant bias. Finally, it does not require modifications to the analytical pipeline recommended by the supplier, enabling a 24-7 availability without disrupting routine monitoring of HbA1c in the laboratory.

Sickle Cell Trait As a Risk Factor for Leukemia: A Nationwide Study

INTRODUCTION: Leukemia is a cancer of blood-forming cells. It can arise from cells of lymphoid or myeloid lineage. It can arise from genetic mutations in tumor suppressor genes, proto-oncogenes or both. It affects over two million people worldwide. A combination of genetic factors and extrinsic factors are believed to play a role. Sickle cell disease (SCD), an inherited disorder leading to the formation of abnormal hemoglobin (HbS) and red blood cell sickling, has been shown to increase the risk for leukemia, presumably due to an increased bone marrow turnover rate. We aimed to explore if sickle cell trait (SCT), when people inherit only one of the two sickle cell genes, is associated with an increased risk for leukemia. METHODS: In this case-control study, we evaluated an association between leukemia (and its subtypes) and SCT in a nationwide cohort of hospitalized patients included in the National Inpatient Sample (NIS) 2016-2019 database. The inclusion criteria for cases were patients who had any of the following ICD-10-CM codes for leukemia: C91 (lymphoid leukemia), C92 (myeloid leukemia), C93 (monocytic leukemia), C94 (other leukemia of specified cell type), and C95 (leukemia of unspecified cell type). The exclusion criteria were Down syndrome (Q90), Fanconi anemia (D61.09), ataxia-telangiectasia (G11.3), Bloom syndrome (Q82), myelodysplastic syndrome (D46), lymphoma (C81, 85), and solid malignancies (C00-75) as these diseases and/or their treatments are known to increase the risk for leukemia independently of SCT (ICD-10-CM D57.3). The controls included patients in the NIS database who do not have the ICD-10-CM codes for leukemia and meet the exclusion criteria applied to the cases. For each year, we used a 1:4 propensity score matching routine. Our match variables were sex, the six race categories used by NIS, and 11 age groups. Four perfect matches (controls) were identified for each case (‘any leukemia’ diagnosis). Patient characteristics were compared using Pearson chi-squared test. Odds ratios (ORs) were calculated for ‘any leukemia’ diagnosis, as well as for each subtype of leukemia. Five multivariate logistic regression models were used to examine the relationship between the leukemia subtypes and SCT while controlling for age group, sex, and race. RESULTS: We identified 181,676 cases and 726,704 controls. The mean age of subjects was 59 years. The majority of subjects (56%) were male. A greater proportion of patients with SCT were found among cases (0.12%) compared to controls (0.08%) (p &amp;lt; 0.0001). The OR for ‘any leukemia’ was 1.48 (95% CI 1.27-1.73, p &amp;lt; 0.0001). When the association between SCT and specific subtypes of leukemia was evaluated, it was statistically significant for myeloid and monocytic leukemias, OR 1.74 (95% CI 1.40 - 2.17) and 2.20 (95% CI 1.09 - 4.42) correspondingly. CONCLUSION: Our case-control study revealed statistically significantly higher odds of SCT among patients with any leukemia (and specifically myeloid and monocytic leukemias) as compared to controls which can be postulated to the common myeloid progenitor lineage of erythrocytes. Our results suggest that, similarly to SCD, SCT although a benign condition can increase the risk for leukemia. To better understand this association, future prospective studies are needed for the mapping of individual risk factors and examining the HbS% levels in SCT carriers who go on to develop leukemia.

Validation of Townes As Mice As a Model of Chronic Kidney Disease and Venous Thrombosis Associated with Sickle Cell Trait

Individuals with sickle cell trait (SCT) are heterozygous carriers of the sickle beta-globin gene. Systematic analyses of large cohort studies over the past decade have established that SCT is a risk factor for a limited number of complications, most notably chronic kidney disease (CKD) and venous thrombosis (VT). SCT red blood cells (RBCs) can undergo sickling, although the degree and duration of hypoxia required to produce sickling are much greater than in sickle cell disease due to the lower intra-erythrocyte sickle hemoglobin beta (HbS) concentration of 25-45%. Hypoxia-mediated HbS polymerization can be enhanced by cellular dehydration, hyperosmolarity and/or acidosis that may be encountered in the renal inner medulla. Furthermore, prolonged exposure of SCT RBCs to profound hypoxia, such as in the nidus of a venous clot, will also result in sickling. The objective of this study was to determine if Townes AS mice manifest kidney dysfunction analogous to their SCT human counterparts. Furthermore, we evaluated whether VT was more pronounced in a well-described model of inferior vena cava (IVC) stasis. We used humanized male sickle cell trait (AS) and age-matched genetic control (AA) mice (n=7-16). Analysis of urinary renal biomarkers (albuminuria, proteinuria, kidney injury marker 1 (KIM-1), osmolality) and kidney function (transcutaneous measurement of glomerular filtration rate (GFR)) were conducted at 4-week intervals from 8 to 40 weeks of age. VT was induced by complete occlusion of the IVC in AA and AS mice. Sickling of RBCs was determined by histological and electron microscopy analysis of the IVC clot. Senicapoc, an oral Gardos channel inhibitor, was administered twice daily (20mg/kg, bid) for 2 weeks to prevent AS RBC dehydration and subsequent sickling. Human HbS accounts for 30.1% of total Hb expression in AS mice. Consistent with human SCT, peripheral blood counts did not differ from AA controls. Basal plasma thrombin-antithrombin complex levels were also not different between AA and AS mice. We performed a longitudinal study of renal structure and function in AA and AS mice over 40 weeks. At 8 weeks of age, AS mice exhibited no differences in any parameter compared to AA controls. However, AS mice subsequently developed albuminuria and a moderate but statistically significant increase in GFR (Figure 1). At 36 and 40 weeks of age, we observed progressive loss of kidney function demonstrated by statistically significant decreased GFR accompanied by a significant increase in albuminuria in AS mice (Figure 1). Over time, proteinuria gradually increased in AS mice, and had doubled by 40 weeks of age compared to AA controls (4.6 ±1.1 vs. 2.3 ±0.4 mg/24h, p&amp;lt;0.05). Increased levels of urinary KIM-1, a marker of tubular damage, were observed in AS mice throughout the duration of the study, with the highest levels at 16 weeks (228.3 ± 32.6 pg/24h vs. 53.8 ± 8.5 pg/24h, respectively, p˂0.05). Urine osmolality was not different at 8 weeks of age, but progressively declined in AS mice with statistically significant changes vs. controls starting at 24 weeks until the end of study (1946 ±63 vs. 2672 ±135 mOsm/kg at 40 weeks, p=0.002). Histologic analysis confirmed glomerular injury (congestion, glomerulosclerosis) and tubular injury (medullary congestion, interstitial fibrosis) in 40 week old AS mice. Following 24 hours of IVC stasis, thrombus weight was significantly increased (p&amp;lt;0.01) in AS mice (mean±SEM; 29.0 mg +/- 1.7; n=8) compared to AA controls (20.0 mg ± 1.7; n=7). Histologic and electron microscopic evaluation demonstrated that severe hypoxia (pO 2 ≈ 10 mm Hg) present in the nidus of venous thrombi was associated with extensive sickling of RBCs in AS mice. To determine if the enhancement of VT observed in AS mice was mediated by RBC sickling, mice were pretreated with Senicapoc or vehicle. Compared to vehicle-treated AS mice (27.3 mg ± 2.2 n=9) pre-treatment with Senicapoc significantly reduced (p&amp;lt;0.05) clot weight (18.1mg ± 1.1; n=7) to that observed in untreated AA controls. In aggregate, our data demonstrate that Townes AS murine nephropathy closely mimics the renal abnormalities (impaired urinary concentration and albuminuria with later onset loss of GFR) described in humans with SCT. Furthermore, we have established a mouse model of the venous thrombotic complications associated with SCT and have demonstrated that hypoxia-induced sickling of RBCs may contribute to enhanced VT observed in AS mice.

Sickle Cell Trait Is Associated with Adverse Clinical Outcomes in a Matched Case-Control Study at a Tertiary Care Center

Background: Sickle cell trait (SCT) is a common condition affecting more than 300 million individuals worldwide and 3 million in the United States. Although generally believed to be an asymptomatic condition, there is growing data to suggest potential associations with morbidity, including risk for venous-thromboembolic events and chronic kidney disease. Methods: We conducted this retrospective cohort study using electronic health record data from the University of Colorado Health Data Compass data warehouse. Patients with a coded diagnosis of SCT were analyzed for SCT-related clinical outcomes compared against a 1:1 randomized matched sample of controls without a history of SCT (matched on age, race, sex). Individuals with sickle cell disease, Sickle-cell/Hb-C disease, sickle-thalassemia, other sickle cell disorders, and hemolytic anemias were excluded from both case and control groups. Outcomes included chronic kidney disease (CKD), deep vein thrombosis (DVT), pulmonary embolism (PE), hematuria, rhabdomyolysis, and splenic infarction. Multivariate logistic regression was used to examine the association of each condition based on SCT carrier status, adjusting for age, sex, and race. Results: We included 1447 SCT patients with complete demographic data, along with 1447 matched controls (n = 2894). There were 1019 (70.4%) women and 428 (29.6%) men in each case and control group. A majority (72.7%) were black or African American. The median age of the cohort was 36 years (IQR = 28 - 47). We found significant associations for CKD (OR = 2.95, 95% CI: 2.03 - 4.30), DVT (2.54, 95% CI: 1.42 - 4.54), PE (OR=4.25, 95% CI: 2.43 - 7.45), and hematuria (OR= 2.28, 95% CI: 1.57 - 3.31). (Table) Despite few overall events and wide confidence intervals, association remained significant for rhabdomyolysis (OR=3.32, 95% CI 1.07 - 10.24) and splenic infarction (OR=44.9, 95% CI 6.15 - 328.00). Male sex was strongly associated with splenic infarction (OR = 8.70, 95% CI 4.11 - 18.41) and rhabdomyolysis (OR = 19.14, 95% CI 4.35 - 84.18). Conclusion: In this case-control cohort study we found significantly increased risk for CKD, DVT, PE, hematuria, rhabdomyolysis, and splenic infarction for patients with sickle cell trait with odds ratios similar to those seen in other study cohorts. The significant morbidity associated with this common genotype warrants further research into primary prevention of SCT associated adverse outcomes.