Prenatal detection of cystic fibrosis

Previous studies in our laboratory have suggested that measurement of methylumbelliferylguanidinobenzoate (MUGB) reactive proteases in midtrimester amniotic fluid is potentially of value for the intrauterine detection of cystic fibrosis. Thirty-nine pregnancies of obligate heterozygotes of cystic fibrosis and 12 cases where one parent has a sib with cystic fibrosis have been previously monitored by means of quantitative and qualitative measurements of MUGB in amniotic fluid. In all but one case the diagnosis was accurately ascertained in the midtrimester and confirmed after delivery. The measurement of MUGB reactivity in midtrimester amniotic fluid by three different procedures--quantitative analysis, polyacrylamide isoelectric focusing, and column filtration--appears to provide a practical and reliable approach for the intrauterine detection of cystic fibrosis.