Five adults with mild sickle cell anemia share a β^s chromosome with the same haplotype

Five adult SS patients from Qatar, Turkey, and South Africa with mild disease, had greatly elevated Hb F and specific patterns of polymorphic sites on their (β^s chromosomes. One subject had an α‐thalassemia (–α/–α). The haplotypes were the common type # 19, associated with severe disease, and type # 31, not seen thus far in an SS patient (numbering system of Antonarakis et al [2]). The data suggest that modifications in the DNA of the β^s # 31 chromosome promotes the synthesis of γ chains.