To study the influence of the β globin locus control region (LCR) genotypic background on the phenotype modifying role of BCL11A polymorphisms, 100 cases of thalassemia, 48 homozygous for the A allele and 52 homozygous for the G allele at the 5'HS4-LCR palindromic polymorphic site were genotyped for two BCL11A single nucleotide polymorphisms (rs11886868 and rs766432) in the intronic region of this gene.