Cystic fibrosis: present status and future prospects in detection of patients and carriers.

Development of a sensitive, easily performed, reliable test would be an important advance in detecting cystic fibrosis, improving genetic counselling and providing early effective treatment. The sweat chloride test, which is reliable in diagnosis, is technically too difficult for a screening program, and only reliably detects homozygotes. In contrast, the meconium test for detecting homozygote newborns is simple, inexpensive, reasonably specific but its general application has yet to be evaluated. Detection of serum components is the basis of two new tests to distinguish patients with cystic fibrosis and carriers. The effect of these serum components on ciliary activity is the principle of one test, an extremely difficult procedure that is subjective and lacks sufficient specificity for routine use. The second test, in which serum components are separated by isoelectric focusing, may provide an objective biochemical means of detecting both homozygotes and heterozygotes.