Prenatal diagnosis of cystic fibrosis by trehalase enzyme assay in amniotic fluid

Abstract

Amniocentsis and amniotic fluid trehalase enzyme assay were offered to 14 pregnant women at a 1 in 4 risk for a child with cystic fibrosis. Of these pregnancies, 12 were screened at the 18th wk of gestation; 10 proceeded to term, 7 following the finding of a normal trehalase activity and 3 despite the low enzyme level in amniotic fluid. In all 10 cases prenatal diagnosis was correct. In 2 cases with low enzyme activity parents opted for termination at the 19th wk, and with PAS [periodic acid-Schiff]-Alcian Blue staining some slight histochemical lesions characteristic of cystic fibrosis were seen in the exocrine glands, including the pancreas and intestinal mucosa, of both fetuses. The total protein content in the meconium of these fetuses was significantly higher than in the controls. Trehalase assay in the amniotic fluid may be a potential prenatal test for cystic fibrosis and it appears that in fetuses with cystic fibrosis some histochemical and biochemical abnormalities can be observed with as early as the 19th wk of gestation. The role of ultrasound examination as an additional procedure for the prenatal diagnosis of cystic fibrosis is also discussed.