Prospective prevention of neonatal hyperammonaemia in argininosuccinic acidura by arginine therapy.

Argininosuccinic aciduria, due to deficiency of argininosuccinic acid lyase, is generally associated with severe neonatal hyperammonaemia and its neurological sequelae. The cases of two siblings with this autosomal recessive disorder are presented. Both infants were preterm and delivered by Caesarean section for maternal pre-eclampsia. The first infant was not diagnosed until after the development of severe hyperammonaemia and, despite adequate treatment with haemodialysis and arginine infusion, remained comatose for a prolonged period. At 20 months she has profound developmental delays and intellectual impairment. The second infant, whose diagnosis was made antenatally by amniotic fluid analysis, was treated with arginine infusion beginning at 32 h of life and never developed hyperammonaemia. We conclude that early recognition and prompt institution of arginine therapy is an effective regimen for the prevention of neonatal hyperammonaemia in argininosuccinic aciduria.