Prenatal diagnosis of cystic fibrosis by microvillar membrane enzyme analysis in amniotic fluid.

Prenatal diagnosis was performed in 92 pregnancies high-risk for cystic fibrosis during six years. Amniotic fluid samples obtained by amniocentesis were examined with regard to their microvillar membrane enzyme activity. Though trehalase, alkaline phosphatase isoenzymes and L-gamma-glutamyltransferase in the amniotic fluid are not specific markers of cystic fibrosis, their activity is significantly lower than in normal pregnancies. By measuring the three enzymes simultaneously, sensitivity, specificity and reliability of the method were found to be over 92%. It is concluded that mid-trimester amniotic fluid diagnosis is indispensable for some heterozygotic couples for cystic fibrosis even in the possession of DNA (desoxyrobonucleic acid) methods.