Human pancreatic alpha-amylase: phenotypic codominance and new electrophoretic variants.

The genetic heterogeneity of human pancreatic alpha-amylase (alpha-1,4-glucan 4-glucanohydrolase, E.C. 3.2.1.1) has been better defined through the development of an asparagine buffered electrophoretic gel system. Three alleles had been identified for the pancreatic amylase locus, AMY2, with two variant alleles as autosomal dominant traits on Tris HCl buffered sheet gels. The asparagine buffered sheet gel now allows the differentiation of the genotypes AMY2B/AMY2B,AMY2B/AMY2A, and AMY2B/AMY2C, thus classifying these three alleles as codominants. Asparagine buffered polyacrylamide gels and thin layer polyacrylamide isoelectric focusing aided in the identification of three new pancreatic amylase variants: AMY2D,AMY2E, and AMY2F. AMY2E has been identified only in AMY2B and AMY2E individuals. This allele is proposed as a quantitative activity variant with essentially the same electrophoretic mobility as AMY2A. The other new autosomal variants have each been identified in single white families. AMY2D is dominant and AMY2F is a codominant trait as shown on thin layer polyacrylamide isoelectric focusing gels.