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Original Contribution
June 23, 1978

Intermediate-Range Sweat Chloride Concentration and Pseudomonas Bronchitis: A Cystic Fibrosis Variant With Preservation of Exocrine Pancreatic Function

Author Affiliations

From the Departments of Pediatrics (Drs Stern, Boat, Matthews, Wood, and Doershuk) and Pathology (Drs Abramowsky), Case Western Reserve University School of Medicine, Cleveland, and the Rainbow Babies and Childrens Hospital (Drs Stern, Boat, Matthews, Wood, and Doershuk), Cleveland.

JAMA. 1978;239(25):2676-2680. doi:10.1001/jama.1978.03280520048017

We studied the clinical and laboratory characteristics of seven patients with sweat chloride concentrations 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.

(JAMA 239:2676-2680, 1978)