DNA haplotypes in Africans and West Indians with sickle cell anaemia or SC disease.

Considering that genetic variation linked to the beta S mutation may influence the clinical manifestations of sickle cell disease, we have analyzed the beta globin cluster haplotypes in 47 patients with this condition (33 SS homozygotes, one S/beta thal (0), and 13 SC) living in London (30 West Indian, 17 West African). Of the 80 chromosomes tested, 82.5% had the Benin haplotype and of the 13 C chromosomes tested, 85% had the Bantu-A4 haplotype. A minority of patients had Bantu or Senegal haplotypes, and in 5 patients we found new haplotypes called E, H and O which may have arisen through mutation or recombination. Because of the predominance of a single haplotype (Benin) nearly all our homozygous S patients were either homozygous or heterozygous for this haplotype. We concluded that the beta globin haplotype is unlikely to be an important determinant of the clinical severity in this patient population.