Prenatal diagnosis of cystic fibrosis by chorionic villus sampling using 12 polymorphic deoxyribonucleic acid markers

This report describes the application of a genetic prenatal diagnostic test for cystic fibrosis to a family with a cystic fibrosis-affected child. The test uses 12 deoxyribonucleic acid (DNA) markers that bracket the cystic fibrosis gene on chromosome 7, and chorionic villus tissue as a source of DNA from the fetus at risk for cystic fibrosis. The fetus was predicted by DNA analysis to be unaffected (although a carrier of one cystic fibrosis gene); this diagnosis was confirmed postnatally by the standard sweat electrolyte test. The genetic linkage test is informative in more than 99% of families with cystic fibrosis-affected members and is also useful for determination of carrier status. The test is both more informative and more accurate than one based upon the markers Met and D7S8 (J3.11) alone. The analysis can be done directly from chorionic villus tissue, and therefore can provide a diagnosis as early as nine to 12 weeks after conception.