Brazilian Sickle Cell Anemia Patients Research Articles

Polymorphisms in the heme oxygenase-1 and bone morphogenetic protein receptor type 1b genes and estimated glomerular filtration rate in Brazilian sickle cell anemia patients.

IntroductionMutations affecting genes involved in oxidative and signaling pathways may be associated with kidney disease in sickle cell anemia. We determined the allele and genotype frequencies of some polymorphisms in the promoter regions of the Heme Oxygenase-1 (HMOX1) [rs2071746 (A > T) and (GT)n repeats, short (S) and long (L) alleles] and Bone Morphogenetic Protein Receptor type-1B (BMPR1B) [rs17022863 (A > G), rs4331783 (A > G) and rs1470409 (A > G)] genes in 75 adult patients with sickle cell anemia and 160 healthy controls and investigated whether these polymorphisms may influence the estimated glomerular filtration rate for the patients.MethodsThe single nucleotide polymorphisms were genotyped using the TaqMan assays, the HMOX1(GT)n repeats were determined by polymerase chain reaction fragment size analysis and the estimated glomerular filtration rate was calculated by the Modification of Diet in Renal Disease formula.ResultsRegarding the HMOX1rs2071746, the estimated glomerular filtration rate median was significantly higher in TT patients (p = 0.019), including when TT was compared with AT + AA (p = 0.009); for the (GT)n repeats, the estimated glomerular filtration rate medians of SS, SL and LL significantly differed (p = 0.009), being the LL estimated glomerular filtration rate median significantly higher, when compared with the LS + SS (p = 0.005). These results suggest that both the homozygotes, TT for rs2071746 and LL for (GT)n repeats, lead to a higher risk of developing renal complications. Concerning the BMPR1B, the frequencies of GG for rs17022863 and AA for rs4331783 were significantly higher in patients than in controls (p = 0.002 and p = 0.008, respectively), however no association with estimated glomerular filtration rate was found.ConclusionThese results contribute to a better understanding of the genetic factors related to the development of nephropathy in sickle cell anemia patients.

Endothelial Nitric Oxide Synthase (eNOS) Gene Polymorphisms and Markers of Hemolysis, Inflammation and Endothelial Dysfunction in Brazilian Sickle Cell Anemia Patients.

The impaired bioavailability of endogenous nitric oxide (NO) in sickle cell anemia (SCA) may be influenced by polymorphisms in the endothelial nitric oxide synthase gene (eNOS). We compared allelic/genotypic frequencies of the eNOS polymorphisms T-786C, VNTR4a/b and G894T between 89 adult SCA patients and 100 healthy controls, and investigated the relationship between these SNPs and markers of hemolysis [lactate dehydrogenase (LDH), indirect bilirubin (IB) and reticulocyte counts], inflammation [interleukins IL-1β, IL-6, IL-8, Tumor Necrosis Factor (TNF-α) and C-reactive protein (CRP)] and endothelial dysfunction (ED) [soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble L-selectin (sL-selectin), von Willebrand Factor (vWF) antigen and D-dimers] in the patients. The frequencies of the mutant -786C allele and -786C/C genotype were significantly higher in patients (p = 0.02 and p = 0.04, respectively) but not significantly correlated with the markers. For VNTR4a/b and G894T, the allelic/genotypic frequencies did not statistically differ between patient and control groups. Patients carrying the 4a allele and those with the 894G/G genotype showed a significant decrease in IB (p = 0.02 and p = 0.04, respectively), and only patients with the 4a allele exhibited reduced IL-1β (p = 0.01). The correlation profiles between markers of inflammation and ED significantly differed between patients carrying the mutant alleles and those with wild-type genotypes. This appears to be the first report on the relationship between eNOS gene polymorphisms and markers of hemolysis, inflammation and ED in Brazilian SCA patients. Our results indicate that the SNPs analyzed may influence the phenotypic variability of these patients.

Evaluation of Markers of Intravascular Hemolysis and Endothelial Dysfunction in Sickle Cell Anemia Patients with and without Hydroxyurea Therapy

Background: Sickle cell anemia (SCA) is characterized by chronic hemolysis and endothelial dysfunction (ED). Plasma hemoglobin (pHb) and its heme component released from intravascular hemolysis (IH) are among the most important factors contributing to ED. Unfortunately, the importance of IH to the development of an ED and the effects of hydroxyurea therapy on IH and ED in SCA remains unclear. Aims: We evaluated plasma levels of IH and ED markers among Brazilian SCA patients not receiving hydroxyurea therapy (HbSS), and compared with those of hydroxyurea-treated SCA patients (HbSS_HU) and healthy controls (HbAA). Methods: A cross-sectional study of 60 SCA consenting patients (32 HbSS and 28 HbSS_HU; 19-42 years) in steady state, who are being followed up at the Blood Center, Pernambuco (HEMOPE) and 32 HbAA controls. The IH markers were serum Lactate Dehydrogenase [LDH] and total heme measured by enzymatic colorimetric tests, and pHb measured by enzyme-linked immunosorbent assay (ELISA). The ED markers were plasma von Willebrand factor (vWF:Ag) and vWF ristocetin cofactor activity (vWF:Rco) levels measured by the latex enhanced immunoassay. The other ED markers were the antigen of vWF-cleaving protease (ADAMTS13:Ag), thrombospondin-1 and endothelin-1 levels measured by ELISA, and ADAMTS13 Activity (ADAMTS13:Act) measured by FRETS-VWF73 method. The study was approved by the Ethics Committee of the State University of Campinas and HEMOPE under protocol No: 1.863.428. Data were analyzed using GraphPad Prism 6. Results: The pHb and LDH were significantly increased in HbSS than HbSS_HU patients (Figures 1A and 1B). Plasma levels of vWF:Ag, vWF:Rco, serum levels of total heme, thrombospondin-1 and endothelin-1 were significantly increased in HbSS and HbSS_HU patients compared to HbAA controls (Figures 1C and 2A, 2B, 2E, 2F), while serum level of thrombospondin-1 level was elevated in HbSS than HbSS_HU patients (Figure 2E). Similarly, ADAMTS13:Ag levels and ADAMTS13 activity were significantly lower in HbSS and HbSS_HU patients than HbAA controls, while ADAMTS13 activity levels were significantly elevated in HbSS_HU patients compared to HbSS patients (Figure 2D). In HbSS_HU patients, the ADAMTS13:Act was negatively correlated with heme and LDH [r = -0.47, p = 0.013; and r = -0.44, p = 0.023 respectively]. In additional, heme was positively correlated with vWF:Ag and LDH [(r = 0.47, p = 0.017) and (r = 0.56, p = 0.003) respectively]. In HbSS patients, LDH and pHb were positively correlated (r = 0.44, p = 0.014). Conclusions: Hydroxyurea therapy was associated with a reduced levels of LDH, pHb and thrombospondin-1 levels, and increased levels of ADAMTS13 activity in SCA patients. Increased ADAMTS13 activity levels may be attributed to reduction of pHb and thrombospondin-1 levels because previous invitro studies have shown that thrombospondin-1 or pHb are bound to vWF. Thus, vWF is restrained from ADAMTS13 activity and cleavage, and hyperreactive vWF might accumulate as a consequence of inhibition of ADAMTS13 activity. Increased thrombospondin-1, pHb and hyperreactive vWF levels are proposed to participate in sickle cell adhesion and promote thrombotic complications. Therefore, our results demonstrate an additional clinical benefit for the use of hydroxyurea in these patients. Disclosures No relevant conflicts of interest to declare.

Whole-exome sequencing indicates FLG2 variant associated with leg ulcers in Brazilian sickle cell anemia patients.

Although sickle cell anemia results from homozygosity for a single mutation at position 7 of the β-globin chain, the clinical aspects of this condition are very heterogeneous. Complications include leg ulcers, which have a negative impact on patients’ quality of life and are related to the severity of the disease. Nevertheless, the complex pathogenesis of this complication has yet to be elucidated. To identify novel genes associated with leg ulcers in sickle cell anemia, we performed whole-exome sequencing of extreme phenotypes in a sample of Brazilian sickle cell anemia patients and validated our findings in another sample. Our discovery cohort consisted of 40 unrelated sickle cell anemia patients selected based on extreme phenotypes: 20 patients without leg ulcers, aged from 40 to 61 years, and 20 with chronic leg ulcers. DNA was extracted from peripheral blood leukocytes and used for whole-exome sequencing. After the bioinformatics analysis, eight variants were selected for validation by Sanger sequencing and TaqMan® genotyping in 293 sickle cell anemia patients (153 without leg ulcers) from two different locations in Brazil. After the validation, Fisher’s exact test revealed a statistically significant difference in a stop codon variant (rs12568784 G/T) in the FLG2 gene between the GT and GG genotypes ( P = 0.035). We highlight the importance of rs12568784 in leg ulcer development as this variant of the FLG2 gene results in impairment of the skin barrier, predisposing the individual to inflammation and infection. Additionally, we suggest that the remaining seven variants and the genes in which they occur could be strong candidates for leg ulcers in sickle cell anemia. Impact statement To our knowledge, the present study is the first to use whole-exome sequencing based on extreme phenotypes to identify new candidate genes associated with leg ulcers in sickle cell anemia patients. There are few studies about this complication; the pathogenesis remains complex and has yet to be fully elucidated. We identified interesting associations in genes never related with this complication to our knowledge, especially the variant in the FLG2 gene. The knowledge of variants related with leg ulcer in sickle cell anemia may lead to a better comprehension of the disease’s etiology, allowing prevention and early treatment options in risk genotypes while improving quality of life for these patients.

Interleukin-27 and interleukin-37 are elevated in sickle cell anemia patients and inhibit in vitro secretion of interleukin-8 in neutrophils and monocytes

Background and objectiveInflammation is implicated in the pathogenesis of most complications seen in sickle cell anemia (SCA) patients. We aimed to evaluate serum levels of two newly discovered anti-inflammatory cytokines (IL-27 and IL-37), and pro-inflammatory cytokines among Brazilian SCA patients that are not on hydroxyurea therapy (HbSS), compared with hydroxyurea-treated patients (HbSSHU) and healthy controls (HbAA). Furthermore, we demonstrated the effect of IL-27, IL-37, and heme on in vitro secretions of IL-8 in human neutrophils and monocytes. MethodsA cross-sectional study of 82 consenting SCA (35 HbSS and 47 HbSSHU) patients in steady state and 49 HbAA consenting individuals. Clinical details were obtained from interviews and medical records. Serum levels of IL-27, IL-37, TGF-β, TNF-α, IL-1β, IL-6, and IL-8 were quantified by enzyme linked immunosorbent assay (ELISA). Neutrophils and monocytes were isolated from healthy controls, and cultured separately with or without cytokines (IL-27 and IL-37) and heme. Supernatant IL-8 concentration was determined by ELISA. ResultsSerum levels of IL-27, IL-37, IL-1β, IL-6, and IL-8 were significantly elevated in HbSS patients compared to HbAA controls. Serum IL-8 levels were significantly higher in HbSS and HbSSHU patients than in controls. IL-27 and IL-37 were positively correlated in both HbSS and HbSSHU patients. In vitro IL-8 production by IL-27 and IL-37 pre-treated neutrophils and monocytes was significantly inhibited even after heme addition. ConclusionsOur findings show that IL-27 and IL-37, as well as the pro-inflammatory cytokines, are elevated in HbSS patients compared with controls, suggesting that the secretion of these anti-inflammatory cytokines is driven by the presence of pro-inflammatory cytokines. This role is probably sufficient in preventing further cellular or tissue damage but not potent enough to prevent inflammation. Therefore, IL-27 and IL-37 may be potential immuno-targets for ameliorating complications associated with elevated heme levels seen in SCA and other hemolytic anemias.

Frequencies of -308G/A (TNFA) and -509C/T (TGFB1) polymorphisms in sickle cell anemia patients from Brazil

Sickle cell anemia is an affection that causes chronic inflammation, with consequences for vaso-occlusion, oxidative stress and cytokine production. Genetic polymorphisms in markers involved in this process can modulate the inflammatory response, including polymorphisms -308G/A of TNFA (tumor necrosis factor alpha) and -509C/T of TGFB1 (transforming growth factor beta 1), reported to increase TNF-α and TGF-β1 production, respectively. Changes in the cytokine balance are important risk factors for clinical events; consequently, we examined the frequencies of these polymorphisms in 240 Brazilian sickle cell anemia patients from southeast Brazil. PCR-RFLP was used to detect these polymorphisms. The -509C/T (TGFB1) polymorphism was more frequent than -308G/A (TNFA), with allelic frequency of 0.3 for the mutant allele T (TGFB) agaist 0.1 for the mutant allele A (TNFA). These allelic frequencies are similar to those known from populations with ethnicity similar to the Brazilian population. Inheritance of these polymorphisms does not seem to be associated with that of the Hb S mutation; however, this information could be useful in analyses of specific clinical characteristics of sickle cell anemia.

European Chromosome 6 Haplotypes Significantly Augment Fetal Hemoglobin Levels in Brazilian Sickle Cell Anemia Patients: Influence of Four HBS1L-MYB Intergenic Region SNPs

AbstractAbstract 1002Fetal hemoglobin (HbF) levels significantly modulate the severity of the 2 major β-hemoglobin disorders - sickle cell anemia (SCA) and β-thalassemia. Three major quantitative trait loci (QTLs; Xmn1-HBG2, the HBS1L-MYB [HMIP] intergenic region on chromosome 6q23, and BCL11A on chromosome 2p16) account for 20–50% of the common variation in HbF levels in SCA and β - thalassemia patients, and in healthy adults (Thein et al., Hum Mol Genet (2009) 18:R216). Lettre et al. (PNAS (2008) 105:11869) confirmed the influence of SNPs at the BCL11A and HBB loci in an African American cohort and a Brazilian cohort of SCA patients; as well as a significant influence of the HMIP region SNPs (rs7776054, rs9389268 and rs4895441) on HbF expression in the Brazilian SCA cohort. A strong association between HMIP polymorphisms that have a high frequency in the European population and modulation of F cell numbers has been reported (Creary et al., PLoS One (2009) 4:e4218). Given the unusually high admixture of the Brazilian population, the current study aimed to look at the influence of such HMIP markers on HbF production in SCA patients from this population (two regions, in the Northeast and Southeast of Brazil). We studied the influence and frequencies of the HMIP allele marker rs9376090 (that specifically tracks European chromosomes), as well as the rs9399137 marker (that has a much higher frequency in European descendents than in African descendents), as well as two HMIP markers (rs9389269 and rs9402686) that are also common in African descendents. Patients (220 HbSS, aged 12–68 years) were recruited at the Hematology Center, UNICAMP and at Fundação Hemope. The study was approved by the local Ethics Committees and informed consent was provided by all participants. Patients presenting the XmnI Gγ polymorphism (N = 2) were identified and excluded from further analysis, as this polymorphism has a known influence on HbF. The HMIP markers were genotyped by Taqman assays. Percentage HbF levels were determined by HPLC, using the Variant™ Bio-Rad kit, and were log transformed to normalize distribution for regression analyses. For those patients on hydroxyurea (HU) therapy, pre-HU HbF levels were used for analyses. Tests for associations between SNPs and HbF levels were conducted using linear regression models (SPSS v.15), including age and sex as covariates. High minor allele frequencies (MAF) for all four HMIP markers were observed in the population of patients studied (MAF; 0.09, 0.10, 0.12 and 0.12 for the rs9376090, rs9399137, rs9389269 and rs9402686 markers, respectively). For all four SNPs studied, higher levels of HbF were observed for the SCA individuals that were homozygotes for the minor allele, with strikingly higher levels of HbF presented by those individuals that were homozygotes for the rs9376090 and rs9399137 polymorphisms (see Table). The clinical courses of these patients were consistent with the higher levels of HbF observed (data not shown). Significantly higher HbF was also found in heterozygotes for the HMIP SNPs, compared to the major allele homozygotes. The variance in HbF levels due to rs9376090 was 7.1% (β= 0.270; p = 6.36 10−5), due to rs9399137 was 7.1% (β= 0.270; p = 9.59 10−5), due to rs9389269 was 8.3% (β= 0.287; p = 2.31 x10−5) and to rs9402686 was 8.3% (β=0.291; p = 2.18 x10−5). Our results confirm the HBS1L-MYB intergenic region as a key determinant of HbF levels in Brazilian SCA patients. The admixture of the Brazilian population has apparently led to a much higher incidence of European haplotypes at chromosome 6 in this population studied, when compared to the British and Tanzanian SCA populations. Importantly, the presence of these SNPs at the HMIP appears to have a very significant effect on HbF levels in the Brazilian SCA population, with probable clinical benefits.TableHbF Levels in SCA Individuals, according to HMIP genotypesSNP (HBS1L-MYB locus)% HbF (Median ± S.D.)TTTCCCrs93760906.35 ± 4.248.45 ± 3.6317.25 ± 1.63N = 182N = 32N=2p<0.01p<0.05rs93991376.47 ± 4.388.68 ± 3.6317.25 ± 1.63N = 167N=37N = 2p<0.05p< 0.05rs93892696.40 ±4.298.59 ± 3.7012.68 ± 2.45N = 162N = 42N = 5p< 0.01p< 0.05rs9402686GGAGAA6.26 ± 4.288.36 ± 4.6712.68 ± 2.45N =166N = 41N = 5p<0.01p<0.05Significant differences for heterozygotes and homozygotes for the minor allele, compared to the homozygote major allele group are indicated by P values. Kruskal-Wallis test, Dunn's multiple comparison post test. Disclosures:No relevant conflicts of interest to declare.

Interleukin 8 Level, Reticulocyte Counting and aPTT Ratio in Brazilian Sickle Cell Anemia Patients with Leg Ulcers

Abstract 4835 Background:Sickle cell anemia (SCA) is characterized by a chronic inflammatory state in which oxidative stress, particularly in the endothelium, exerts a strong influence on the pathogenesis of vaso-occlusion and may be implicated in patients' clinical heterogeneity and survival. It has been suggested that the cytokine production profile of cells involved in the immune response may vary among patients with SCA. Leg ulcers (LU) represent a severe complication in these patients, and this condition has been associated with specific end-organ damage and an increase in morbidity and mortality. Recent studies have shown that venous obstruction, endothelial dysfunction, coagulopathy and infections are implicated in the complex pathogenesis of LU. Aims:To determine IL-1β, IL-6 and IL-8 plasma levels and gene expression rates as well as hematological and coagulation parameters and correlate these with the history of LU in adult SCA patients followed up at HEMOPE, in the state of Pernambuco, northeastern Brazil. Methods:Peripheral blood samples from 92 patients (median age 27 years; 42 female; 52 male; all Afro-descendants) in the steady state who had been diagnosed with SCA (HbSS), had not received a transfusion and were not using hydroxyurea were analyzed. Plasma levels of cytokines were determined by ELISA, and the gene expression rates by qRT-PCR. The patients' clinical and laboratorial characteristics were obtained from their medical charts. Statistical analysis was performed using the SAS System for Windows version 9.2. Results:Median age was higher in patients with a history of LU than in those without a history (33.1 vs. 28.4; p = 0.04). Although no statistically significant (p = 0.5) differences in IL-8 gene expression rates were observed, IL-8 plasma levels were significantly higher in patients with a history of LU than in patients without a history (23.8 vs. 7.7; p = 0.01) (Figure 1). Thus, patients with high levels of IL-8 had an increased risk for the occurrence of leg ulcers (OR = 1.01; 95% CI = 1.00–1.02). The ROC curve showed that IL-8 levels higher than 8.55 pg/mL could indicate the presence of LU (accuracy = 71.6%; sensitivity = 73.7%; specificity = 68.5%). The laboratory tests revealed reticulocyte counts and activated partial thromboplastin time (aPTT) ratios (R) that were significantly higher in patients with a history of LU than in those without a history (11.8 vs. 8.4, p = 0.01; 1.1 vs. 0.9, p = 0.04, respectively). Both the higher reticulocyte counts and R values were associated with increased risk for the occurrence of leg ulcers in these patients (OR = 1.12, 95% CI = 1.02 – 1.20; OR = 24.28, 95% CI = 1.20 – 486.09, respectively). Conclusion:In this study, patients who had had LU at some time in their lives showed significantly higher IL-8 levels, reticulocyte counts and R values than patients who had never had LU. Our results therefore suggest a relationship between the parameters described above and LU in patients with SCA. These parameters could perhaps be used, in association with different genetic modulators that may contribute to different clinical phenotypes observed in this disease, as markers of this clinical manifestation of SCA or of a propensity to develop it. [Display omitted] Financial Support: CAPES (Brazil)/FAPESP/CNPq/INCTS Disclosures:No relevant conflicts of interest to declare.

Promoter region sequence differences in the A and G gamma globin genes of Brazilian sickle cell anemia patients

Fetal hemoglobin (HbF), encoded by the HBG2 and HBG1 genes, is the best-known genetic modulator of sickle cell anemia, varying dramatically in concentration in the blood of these patients. This variation is partially associated with polymorphisms located in the promoter region of the HBG2 and HBG1 genes. In order to explore known and unknown polymorphisms in these genes, the sequences of their promoter regions were screened in sickle cell anemia patients and correlated with both their HbF levels and their betaS-globin haplotypes. Additionally, the sequences were compared with genes from 2 healthy groups, a reference one (N = 104) and an Afro-descendant one (N = 98), to identify polymorphisms linked to the ethnic background.The reference group was composed by healthy individuals from the general population. Four polymorphisms were identified in the promoter region of HBG2 and 8 in the promoter region of HBG1 among the studied groups. Four novel single nucleotide polymorphisms (SNP) located at positions -324, -317, -309 and -307 were identified in the reference group. A deletion located between -396 and -391 in the HBG2 promoter region and the SNP -271 C-->T in the HBG1 promoter region were associated with the Central African Republic betaS-globin haplotype. In contrast, the -369 C-->G and 309 A-->G SNPs in the HBG2 promoter region were correlated to the Benin haplotype. The polymorphisms -396_-391 del HBG2, -369 SNP HBG2 and -271 SNP HBG1 correlated with HbF levels. Hence, we suggest an important role of HBG2 and HBG1 gene polymorphisms on the HbF synthesis.

A New Sequence Change in the Hs2-Lcr (G→A − 10.677) and Gg-Globin Gene Promoter Region (T→C − 157 and a 4 Bp Deletion − 222 to − 225) in Sickle Cell Anemia Patients with Fetal Hemoglobin Level and bS-Globin Gene Haplotypes Diversity.

The sickle cell anemia has a very high prevalence in Bahia, a state of Brazil. The HbF levels and bS-globin gene haplotypes of 125 sickle cell anemia patients were investigated and the Gγ and Aγ gene promoter and HS2-LCR regions of ten patients were selected for DNA sequence. The study was approved by the Oswaldo Cruz Research Foundation's human research ethics committee. The bS- globin gene haplotypes were investigated using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques; the HbF levels were estimated by high performance liquid chromatography (HPLC). The Gg and Ag-globin gene promoter and HS2-LCR regions were sequenced in an automatic sequencer. The distribution of bS- globin gene haplotypes showed 64 (51.2%) patients with genotype CAR/Ben; 36 (28.8%) Ben/Ben; 18 (14.4%) CAR/CAR; two (1.6%) CAR/Aty; two (1.6%) Ben/Cam; one (0.8%) Car/Cam; one (0.8%) CAR/Arab-India and one (0.8%) Sen/Aty. Among these patients, four CAR/CAR had HbF ≥10.0%; three Ben/Ben had HbF ≤ 5.0%; 11 CAR/Ben had HbF ≥15.0% and 18 had HbF ≤ 5.0%; two Cam/Ben patients had HbF levels ≥15.0%. Ten individuals presenting HbF and bS-globin gene haplotypes diversity were selected to sequence the Gg and Ag-globin gene promoter and HS2-LCR regions. The HS2-LCR sequence analyses demonstrated a G→A change (−10.677) (GeneBank DQ873522) in five sickle cell anemia patients with Ben haplotype and high HbF levels (Table 1); the CAR/Ben and Ben/Ben patients with low HbF levels did not have this sequence variation; among the small patient group investigated, there were two CAR/CAR patients with high HbF levels without this substitution. The Gg gene promoter sequence analyses showed a T→C substitution (−157) (GeneBank DQ873521) among all patients and a 4 bp deletion (−222 to −225) (GeneBank DQ873519) related to Cam haplotype (Figure 1). The HS2-LCR sequence change reported here is located in the proximity to a binding site of the GATA-1 and a ubiquitous trans-acting factor and can constitute a motif associated to the Ben chromosome and may play an important role in g-globin gene transcription regulation. The polymorphic site on Gg-globin gene promoter region can be a common sequence characteristic among the Brazilian sickle cell anemia patients. The results described here suggest new polymorphisms in the HS2-LCR and Gg gene promoter and confirms the genotypic heterogeneity among Brazilian sickle cell anemia patients, justifying further studies to investigate its correlation with HbF synthesis and clinical profile in sickle cell anemia patients. [Display omitted]

African gene flow to north Brazil as revealed by HBB*S gene haplotype analysis

Haplotypes linked to the HBB*S gene were analyzed in a sample of 260 chromosomes of Brazilian sickle cell anemia patients from the population of Belém, state of Pará, to evaluate if the present-day haplotype frequencies correlate as well as expected with historical information on the geographic origin of African slaves sent directly to Northern Brazil. The HBB*S gene haplotype distribution (66% Bantu, 21.8% Benin, 10.9% Senegal, and 1.3% Cameroon) is in agreement with those observed for other Brazilian populations regarding the highest proportion of the Bantu type, followed by the Benin type, but it differs significantly concerning the Senegal type as this haplotype is rare or absent in samples from other Brazilian regions already studied. In addition, our results are in accordance with historical records that establish that about 90% of the slaves sent to Northern Brazil were from Angola, Congo, and Mozambique, where the Bantu haplotype predominates, in contrast to 10% of slaves from Senegambia, Guine-Bissau, and Cape Verde, where the Senegal haplotype is the most common. On the other hand, the observed frequency of the Benin haplotype in Belém was much higher than that expected by historical data. This fact corroborates the suggestion that the high prevalence of the Benin type in Belém is due to domestic slave trade and later internal migrations, mainly from the Northeast, since there are no historical records of direct slave trade from Central West Africa to North Brazil.

Effects of hydroxyurea in a population of Brazilian patients with sickle cell anemia

Fetal hemoglobin (HbF) inhibits the polymerization of sickle hemoglobin, modulating the clinical features of sickle cell anemia (SCA). Hydroxyurea (HU) therapy can increase the HbF level, although its production can be influenced by genetic determinants. Twenty-two Brazilian SCA patients were evaluated over 5 years before and after HU use. We analyzed (1) betaS haplotype; (2) patient characteristics; and (3) toxicity. No differences between age, sex, and HU response were observed. We found 40.9% of homozygous for Bantu haplotype, and, in contrasting to other trials, we observed HbF level increase in this group (3.84-9.08 g/dL, P=0.003). Adverse effects were rare. Labyrinthitis was observed in 2 (9.10%) patients after HU use, although this complication had not been described before.