Unexpected diagnosis of cystic fibrosis at autopsy

What is a cystic fibrosis diagnosis?

Cystic fibrosis (CF) should be considered in patients with a wide variety of clinical presentations and of diverse racial and ethnic backgrounds. In most cases the diagnosis is suggested by manifestations of chronic sinopulmonary disease and exocrine pancreatic insufficiency, and then confirmed by a positive sweat test result. Patients may, however, present with pancreatic sufficiency or other atypical clinical features, sometimes in association with normal or borderline sweat test results. In such cases, the ability to detect CF mutations and to measure transepithelial bioelectric properties can be diagnostically useful. Mutation analysis can also be used for carrier screening, prenatal diagnosis, and newborn screening.

Cyclic AMP-related and cation-affected human platelet chloride transport regulation

Cystic fibrosis has been characterized as a defect in the regulation of cyclic AMP-dependent transepithelial chloride transport. The activation of cyclic AMP-dependent protein kinase A by cyclic AMP occurs normally in cystic fibrosis cells, but they fail to transport chloride ions in response to protein kinase A stimulation. Defective chloride secretion and abnormal electrolyte transport occurs in several organs including the lung, sweat glands, intestine and pancreas. The present work was aimed at exploring whether the same or similar regulatory systems are functional in platelets, and if they are altered or deficient in individuals with cystic fibrosis. Chloride transport in platelets from normal subjects and from cystic fibrosis patients was measured by cell sizing techniques where chloride permeability is the limiting factor. In platelets from healthy volunteers, the chloride channel blocker, 5-nitro-2-(3-phenylpropylamino) benzoic acid, inhibits the transport in a dose-dependent manner. The preservation of chloride transport capability is shown to be dependent upon the presence of either Ca2+ or two divalent cation substitutes, Cd2+ or Cu2+. It is also shown that in normal subjects 0.1 mumol/l prostaglandin E1, which elevates cyclic AMP 6 times and abolishes platelet aggregation, significantly enhances the rate constant of the transport. Furthermore, in five out of nine cystic fibrosis patients studied, platelet chloride transport did not respond to stimulation by prostaglandin E1.