HBS1L and Schnyder corneal dystrophy: BCL11A and HBS1L-MYB are major HbF loci present in all human populations, including in SCD patients [7, 9, 22], but the third, Xmn1-HBG2, residing within the beta-globin gene cluster, is detected only in patients where so-called ‘Senegal’ and ‘Arab-Indian’ haplotypes surrounding the sickle mutation are prevalent.