MYB and Schnyder corneal dystrophy: The eventual level of HbF (α2γ2) in patients with SCD is influenced by cis- and trans-acting single nucleotide polymorphisms (SNPs) in known quantitative trait loci (QTLs) on chromosomes 11 (HBB), 2 (BCL11A) and 6 (HBS1L-MYB), respectively.