Fanconi anemia: prenatal diagnosis in 30 fetuses at risk.

We report our experience, since 1978, with prenatal diagnosis in fetuses at risk for Fanconi anemia. Amniotic fluid cells from 30 fetuses from 24 families were monitored for baseline and diepoxybutane-induced chromosomal breakage. Seven of the fetuses at risk were diagnosed as affected; baseline and diepoxybutane-induced breakage ranged from 0.18 to 0.45 and 0.69 to 0.96 breaks per cell, respectively. The range of baseline and diepoxybutane-induced chromosomal breakage in amniocytes from the 23 pregnancies at risk that were diagnosed prenatally as unaffected ranged from 0 to 0.08 and 0 to 0.13 breaks per cell, respectively. Four of these cases were also diagnosed as normal on the basis of chromosomal breakage studies in cells obtained by chorionic villus sampling. The range of baseline and diepoxybutane-induced breakage in cells from five control fetuses was 0 to 0.05 and 0 to 0.10 breaks per cell, respectively. Of the pregnancies diagnosed as affected, two were carried to term, whereas five were terminated. One newborn and two abortuses had congenital malformations including abnormalities of the thumb and radius. The other affected live-born infant, now 5 1/2 years old, has severe growth retardation and pancytopenia. No Fanconi anemia-associated malformations were found in any of the other fetuses or newborns studied. In all cases in which tissue was available for study, diagnoses were confirmed by chromosome breakage studies. This method thus permits reliable detection of Fanconi anemia.