Prenatal diagnosis of the organic acidurias.

Prenatal diagnosis for the genetic counselling of families at risk for having children with the life-threatening organic acidurias is advancing rapidly. The two major approaches to prenatal diagnosis are the assay for deficient activity of the enzymes in cultured amniocytes and the measurement of increased concentrations of the organic acids in the amniotic fluid. The latter, when done by stable isotope dilution analysis, is rapid, relatively inexpensive and very reliable.