Characterization of beta-globin haplotypes using blood spots from a population-based cohort of newborns with homozygous HbS.

PURPOSE: A population-based cohort from three state newborn screening programs was used to describe beta-globin gene cluster variation.

METHODS

Blood spots from newborns homozygous for HbS were genotyped for five restriction fragment length polymorphisms (RFLPs) to construct beta-globin haplotypes. Haplotype distributions were compared by race/ethnicity and sex. Expected heterozygosities were calculated and compared with observed heterozygosities.

RESULTS

Haplotype distributions did not differ between sexes for either blacks or Hispanics. Neither racial/ethnic group deviated from Hardy-Weinberg equilibrium; however, Hispanics had higher heterozygosity at two RFLPs compared with blacks.

CONCLUSION

The differences between populations probably reflect recent migration and admixture rather than selection.