Abstract
Significant DNA polymorphisms have been reported in the β-globin gene cluster of ε-Gγ -Aγ – ψβ-δ-β-gene region, in normal (Hb AA) individuals and in patients with sickle cell anaemia (SCA). Investigations of the extent of the DNA polymorphisms in the βA- and βS-globin gene cluster using Hind III, Hinc II, Ava II, Xmn I, and Hpa I, revealed several associations with mild SCA. The correlation of the presence (+) or absence (-) of the restriction endonuclease site to clinical severity in patients homozygous for βS-gene showed that the mild form of SCA was associated mainly ( > 90%) with the Xmn I polymorphic site 5′ to Gγ, and to a lesser extent with Hinc II polymorphic site 5′ to ε and in the ψ β-gene, with Hind III polymorphic site in Gγ and Hpa I polymorphic site 3′ to the β-globin gene, while in the severe form of SCA these polymorphic sites were absent in most patients. The polymorphism in the β-globin gene cluster was significantly related to the expression of the βS-gene and clinical severity of SCA.