Genetics of pepsinogen I

A study of 948 Norwegians including 118 matings with 429 children provided evidence that the Pg I group of pepsinogens must be coded for by more than one gene locus. At the Pg5 locus the alleles Pg5N, Pg5F and Pg5S with frequencies 0.644, 0.059 and 0.004, each code for a single electrophoretic isozyme band responsible for Pg phenotypes Pg 5, intense Pg (4) and Pg 5S, and a null-allele Pg5o with frequency 0.293. The Pg 2, Pg 3 and weak Pg 4 bands are not coded for by alleles at the Pg5 locus and differ from the Pg5 gene products in the oligopeptides split off by pepsinogen-pepsin conversion. The Pg5 alleles differ from each other in the pepsin-coding part of the gene. Intensity variations of Pg 5 have no simple genetic explanation.