Restriction site polymorphism in the phosphoglycerate kinase gene on the X chromosome

Using a human phosphoglycerate kinase (PGK) cDNA probe, we have identified a common Pst I restriction site polymorphism on the human X chromosome in all ethnic groups studied. The polymorphic Pst I site was absent in 40.4% of 94 X chromosomes of unrelated subjects. Heterozygous females can only be detected by the combined use of a Pst I digest and a Xba I + Pst I digest due to the presence of autosomal and X-linked bands of the same size in simple Pst I digests. Since 48% of females are heterozygotes for the Pst I polymorphism, this site can serve as a useful genetic marker on the long arm of X chromosome in man.