A single nucleotide substitution in the phosphoglycerate kinase (PGK)-1 gene occurred after the separation of PGK-1 and PGK-2.

The mammalian genome contains two functional loci for the production of phosphoglycerate kinase, PGK-1, an X-linked gene expressed in all somatic cells, and PGK-2, an autosomal intron-less gene expressed exclusively in late spermatogenesis. A nucleotide substitution from guanine to thymine was recently found at position 473 of PGK-1 mRNA in PGK Shizuoka. The mutation was not found in the PGK-2 gene and might have occurred after separation of PGK-1 and PGK-2.