Genetics of human S-adenosylhomocysteine hydrolase. A new polymorphism in man.

A specific staining procedure for the demonstration of S-adenosylhomocysteine hydrolase (SAHH, EC 3.3.1.1) is given. The enzyme has a broad tissue distribution and is also present in erythrocytes. The SAHH gene is polymorphic in the population of southwest Germany with two common alleles: SAHH1 = 0.96 and SAHH2 = 0.04. Family studies resulted in the expected segregation ratios. No evidence for close linkage with a total of 25 marker loci was found. But information from human mouse somatic-cell hybrids led to the localization of the SAHH gene to human chromosome 20, thereby confirming the findings of Hershfield and Francke (1982).