Prenatal diagnosis of cystic fibrosis.
Cystic fibrosis is the most common autosomal recessive genetic disorder in the Caucasian population (1:2000-1:4000) (Warwick, W. J. (1978) Helv. Paediatr. Acta 33, 117-125). This defect is characterized by chronic obstructive pulmonary disease, pancreatic exocrine insufficiency and abnormally high perspiration electrolytes in most patients (Talamo et al. (1985) In: The metabolic basis of inherited diseases, pp. 1887-1917). The elevated electrolyte level provides the most reliable diagnostic test for cystic fibrosis homozygotes. Although prospects for cystic fibrosis patients have improved, genetically homozygous cystic fibrosis is effectively a lethal disease. Because of the seriousness of the disease, many families with one affected child desire a prenatal diagnosis when a second pregnancy occurs. Despite extensive research, the biochemical basis of cystic fibrosis remains unknown. Secondary effects on microvillar enzymes allow second trimester diagnosis (17-18 weeks of gestation (Brock, D. H. J. (1983) Lancet II, 941-943). First trimester prenatal diagnosis for cystic fibrosis became possible with DNA technology. Application of polymorphic marker loci to problems of prenatal diagnosis and carrier-testing is discussed.