Pregnancy and argininosuccinic aciduria.

We present the outcome of a pregnancy in a woman with mild argininosuccinic lyase deficiency to add to the collective experience of the maternal and fetal effects of urea cycle defects. In females affected with argininosuccinic lyase deficiency, careful clinical and biochemical monitoring of pregnancy will minimize the risk of metabolic decompensation in the perinatal period. Furthermore, it would appear that argininosuccinate is not teratogenic to the development of the human fetus.