Serum pancreatic isoamylases in the diagnosis of cystic fibrosis heterozygotes: A non-valuable test.

A group of 102 obligate heterozygotes for the cystic fibrosis gene were examined for genetic type of pancreatic isoamylases as well as enzyme activity of pancreatic iso-amylases, salivary isoamylases and total amylase in serum. The analysis was performed using electrophoretic separation for detection of the various types of isoamylases, and their relative activity was determined by means of densitometry. The activities of salivary isoamylases and total amylase in serum showed no significant differences between the cystic fibrosis heterozygotes and a control group. The frequency of the variant gene for pancreatic isoamylase was also the same as in the controls. The mean value for pancreatic isoamylase was slightly higher in the cystic fibrosis heterozygotes than in the control group (0.05 greater than P greater than 0.02).