Intermediate-range sweat chloride concentration and Pseudomonas bronchitis. A cystic fibrosis variant with preservation of exocrine pancreatic function
R. C. Stern, T. F. Boat, C. R. Abramowsky, L. W. Matthews, R. E. Wood and C. F. Doershuk
We studied the clinical and laboratory characteristics of seven patients
with sweat chloride concentration consistently between 40 and 60 mEq/liter.
Each has chronic Pseudomonas bronchitis, and all lack digestive symptoms.
Laboratory findings indicate the preservation of exocrine pancreatic
function. The patients include two of five children in one family and two
of four in another. In a third family, one of five siblings has an
intermediate sweat chloride concentration, but another has a typical
fibrosis value (105 mEq/liter). One patient died of respiratory failure;
results of an autopsy showed bronchiolectasis typical of cystic fibrosis,
but minimal pancreatic changes. The data suggest a genetic basis for this
variant of cystic fibrosis. These patients may be homozygous for a portion
of a closely linked multigene cystic fibrosis locus or may have modifier
genes that ameliorate the pancreatic and sweat lesions.
