Sickle cell anemia in the state of Maranhão: a haplotype study.

Sickle cell anemia (SCA) is the most severe form of sickle cell disease caused by homozygosity of the β-gene (S/S or ββ) and has worldwide distribution. Six polymorphic sites in the β-globin gene cluster were analyzed from a sample of 56 chromosomes of patients with SCA from the state of Maranhão, northeastern Brazil. PCR-RFLP showed that the CAR haplotype was predominant with a frequency of 64.