6% European, 29.6% African, and 30.8% Native American mean genetic ancestry proportions. SNPs (HBG2, rs748214; BCL11A, rs4671393; HBS1L-MYB,

rs28384513, rs489544 and rs9399137) were determined by a TaqMan SNP genotyping assay (Applied BioSystems, Foster City, CA, USA) according to the manufacturer’s instruction. Pre-designed probes were ordered for genotyping analyses. About 10–50 ng of DNA were amplified with 5 μl of 2X TaqMan Universal Ku-0059436 mouse PCR master mix, 0.5 μl of 40 × primer and TaqMan probe dye mix. Cycling conditions consisted of 10 min at 95 °C, followed by 40 cycles 15 s at 92 °C, 1 min at 60 °C. Allelic discrimination was performed on an Applied BioSystem RT-PCR system. To correct for the skewness of the HbF percentage, the values were log10-transformed to create a nearly normally distributed quantitative trait. The genetic association of this trait Selleck Vincristine with SNP alleles was analyzed through multiple

linear regression (SPSS, Version 12, IBM) with age and sex as covariates. The Mann–Whitney U test was used to determine whether there were differences between the HbF level distribution according to the presence or absence of minor allele frequency (MAF) in the studied loci. An overall significance level of 0.05 was set for statistical analyses. Allele A of rs4671393 (BCL11A) was associated with increased HbF levels and genotypes containing the minor allele exhibited significantly higher HbF levels. In addition, 10% of the trait variance among SCA patients from Northern Brazil was explained by genetic variation

at rs4671393 alone (Table 1 and Table 2). Similar results were observed in Brazilian and African fantofarone American [6], and Tanzanian and African British SCA patients [7]. Our results are also consistent with those seen in African American SCA patients, in whom the minor allele frequency (MAF) was significantly higher in patients with high HbF levels (at least 10%) than in patients with low HbF levels [8]. Another SNP in BCL11A gene correlated with HbF in SCA patients of different ethnicities is rs11886868. However, since these SNPs are in strong linkage disequilibrium, we have chosen to investigate only rs766432, considered to be the one most highly correlated with HbF in SCA populations. HMIP polymorphisms are distributed in three disequilibrium blocks, referred to as HBS1L-MYB intergenic polymorphism (HMIP) blocks 1, 2 and 3. Common alleles within the three haplotype blocks are associated with HbF expression, with block 2 (24 kb) accounting for the majority of the variance [3]. In this study, of the three genotyped SNPs (rs2838451, block 1; rs4895441 and rs9399137, block 2), only rs4895441 was significantly associated with HbF levels, explaining 9.2% of the variation in HbF levels. Genotypes containing the minor allele of this SNP (AG and GG) exhibited significantly higher HbF levels when compared to genotype AA (Table 1 and Table 2).