Prenatal diagnosis of the urea cycle diseases: a survey of the European cases.

A European survey of prenatal diagnosis cases involving urea cycle diseases was performed. Citrullinemia was the most frequently investigated disease (108 cases). Other diseases are, in order of frequency, argininosuccinic aciduria (75 cases), ornithine transcarbamylase defect (52 cases), carbamoylphosphate synthetase defect (8 cases), triple H (3 cases), and arginase deficiency (1 case). Only one disease (ornithine transcarbamylase defect) is presently diagnosed using molecular biology methods.