Supplementary Material for: ANTXR1 Intronic Variants Are Associated with Fetal Hemoglobin in the Arab-Indian Haplotype of Sickle Cell Disease

Disease severity of sickle cell anemia is highly variable, and it is commonly accepted that fetal hemoglobin (HbF) levels play a major role as an ameliorating factor. Investigation of genetic variants have identified several genes to be the principal influencers of HbF regulation. Here, we further elucidated the association of rs4527238 and rs35685045 of ANTXR1 genes in the context of HbF level variance in sickle cell anemia patients of the Arab-Indian haplotype. Samples from 630 sickle cell anemia patients were analyzed for the mutations at 2 specific locations of the ANTXR1 gene by TaqMan®-based real-time PCR. The CC genotype (p = 0.018) of rs4527238 and the TT genotype (p = 0.048) of rs35685045 of ANTXR1 were found to be significantly associated with low HbF expression. The frequency of the CC genotype of rs4527238 was observed to be high in the low HbF patient group compared to the high HbF group (p = 0.009). Likewise, the frequency of the TT genotype of rs35685045 was also high among the low HbF group (p = 0.017). The ANTXR1 genetic mutations and the association with HbF expression in the Arab-Indian haplotype sickle cell patients revealed that the ANTXR1 gene may be a major HbF modulator leading to potential therapeutic options that should be further explored.