Two-dimensional electrophoresis of plasma polypeptides reveals "high" heterozygosity indices

A series of 62 plasma samples have been examined for genetic variation by the technique of two-dimensional polyacrylamide gel electrophoresis followed by silver-staining of the gels. Twenty polypeptides chosen without respect to variability were considered suitable for scoring. Of the total of 1,240 polypeptides, 29 could not be scored unambiguously. Seventy-five of the remaining 1,211 exhibited the combination of a normal and a variant polypeptide. All variants were present in either the father or the mother of the subject. This index of heterozygosity (6.2 +/- 0.7%) is substantially higher than those reported by others in similar studies of human fibroblasts, lymphocytes, kidney, or brain cells.