Congenital nephrosis: detection of index cases through maternal serum alpha-fetoprotein screening.

Congenital nephrosis is an autosomal recessive disorder with an incidence of 1 in 8000 in Finland, but it is quite rare in non-Finnish populations. In families known to be at risk, prenatal detection is possible by means of maternal serum and/or amniotic fluid alpha-fetoprotein levels. We report the antenatal diagnosis of four cases of congenital nephrosis, three of which were index cases, through maternal serum alpha-fetoprotein screening. The diagnosis was confirmed at birth in two infants. Two patients elected to terminate their pregnancies, and the diagnoses were confirmed pathologically (obliteration of foot processes on electron microscopy of fetal glomeruli) in both. In cases of elevated maternal serum alpha-fetoprotein, with unexplained and marked elevations of amniotic fluid alpha-fetoprotein and normal acetylcholinesterase levels, the diagnosis of congenital nephrosis must be considered regardless of ethnic origin.