Update and Review: Cystic Fibrosis.

Cystic fibrosis (CF) is one of the most commonly inherited recessive disorders in U.S. Caucasians, with a carrier frequency of approximately 1 in 29. Genetic counseling and CF mutation analysis has traditionally been offered to the affected patient and his/her extended family, in keeping with policy statements from professional organizations (ASHG, NSGC, ACOG). The target population for CF testing and counseling may be evolving after the release of the 1997 National Institutes of Health Consensus Statement, Genetic Testing for Cystic Fibrosis, which recommends that CF screening be offered to all preconceptional and pregnant couples. Genetic counseling for CF is complicated by reports of polymorphisms in the CF gene that are associated with symptoms that do not meet the diagnostic criteria for CF, such as bilateral congenital absence of the vas deferens, bronchiectasis, and idiopathic pancreatitis. To aid genetic counselors with these issues, this review explores the symptoms of CF, patient management, gene function, genetics, genotype/phenotype correlation, and genetic counseling issues.