Amylase polymorphism: studies of sera and duodenal aspirates in normal individuals and in cystic fibrosis.

Prior genetic studies of the human pancreatic amylase (Amy2) locus have been 
directed principally to the electrophoretic analysis of serum and urine, on 
the assumption that these fluids receive negligible contributions from the salivary 
(Amy 1) locus. In support of that assumption was the observation 
that the isozyme bands were lacking in patients with cystic fibrosis 
and in a postpancreatectomy patient. We have examined the sera of 
97 patients having cystic fibrosis and find normal levels of serum 
amylase. On electrophoresis, three-quarters of the cystic fibrosis patients have a 
pattern (F- pattern) not observed in normal sera. The pattern is 
characterized by the absence of Pa 1. Comparative electrophoresis and mixing 
experiments indicate that the F-pattern is of salivary origin and is 
unmasked in cystic fibrosis by the absence of a pancreatic contribution. 
The normal serum pattern is considered to be an admixture of 
salivary and pancreatic amylase. On the assumption that duodenal fluids might 
more closely reflect the pancreatic (Amy 2) locus, electrophoretic studies were 
performed on 148 normal individuals and 37 individuals with cystic fibrosis. 
Electrophoretic phenotypes in duodenal aspirates are more complex than previously reported 
in studies of urine and serum; presumably because of the higher 
concentrations of amylase in the aspirates. Comparative electrophoresis and mixing experiments 
indicate that the phenotypes observed in duodenal aspirates also reflect admixture 
of pancreatic and salivary amylase. This recognition of pancreatic and salivary 
admixture in sera fortunately does not alter our prior understanding of 
the genetics of the Amy 2 polymorphism. The extensive studies which 
led to the delineation of the Amy 2 polymorphism were essentially 
based on the presence or absence of a variant band which 
proves now to be outside the zone of admixture. 