Detection of a novel DNA polymorphism in the β-globin gene cluster

Analysis of DNA from the β-globin gene cluster in an Albanian family identified a novel RsaI site approximately 550 base pairs 5' to the β-globin gene. In this family, two chromosomes carrying otherwise identical β-globin haplotypes were found to differ at the RsaI site. Population screening demonstrated the presence and absence of the site in DNA from individuals of northern European, Mediterranean, Middle Eastern, Southeast Asian, African, and Asian Indian descent, indicating that this site is a DNA polymorphism common in many ethnic groups. The polymorphism is also present in DNA from individuals carrying different β-globin alleles. Additional nucleotide sequence changes identified in an RsaI(+) genomic clone in the region immediately 3' to the RsaI site suggest a mechanism for the randomization of the site with respect to haplotype.