The amniotic fluid activity of
gamma glutamyl transpeptidase (GGT),
leucine aminopeptidase (LAP) and alcaline
phosphatase (AP) and disacharidases was examined in 66 pregnancies with the risk of
cystic fibrosis (CF) in the 17th-21st weeks of gestation. So far 28 pregnancies continue. The prenatal diagnosis was confirmed in all so far delivered children or aborted foetuses if the GGT activity was higher than 400 U/1 (10th percentile) or lower than 190 U/1 (3rd percentile) in the 17th-18th weeks. The results of other microvillar and ultrasound examinations were consistent with it. From 3 pregnancies with GGT activity in the range of 3-5 percentiles and abnormal activities of other microvillar
enzymes, the CF was confirmed only in one aborted foetus with
meconium ileus and with abnormal ultrasound examination. In other 2 pregnancies with normal ultrasound, healthy children were delivered. In 3 pregnancies with the GGT in the range of 5-10 percentiles and abnormal other microvillar
enzymes, one false negative GGT and ultrasound examination was disclosed. The other 2 aborted foetuses did not exhibit the signs of CF in necropsy examinations. The
meconium ileus was found in 2/4 of aborted foetuses with GGT lower than 3 percentiles, abnormal activities of other microvillar
enzymes and abnormal ultrasound examination. The ultrasound examination was correct in 2/10 of pregnancies with GGT lower than 3 percentiles or abnormal activities of other microvillar
enzymes. The GGT examination in 19th-21st weeks provided similarly reliable diagnostic results. The importance of fetal karyotyping and ultrasound elimination of other severe congenital anomalies is pointed out for critical interpretation of microvillar
enzyme activities testing.(ABSTRACT TRUNCATED AT 250 WORDS)