Evidence for X-Linked Dominant Inheritance of Ornithine Transcarbamylase Deficiency

Abstract

The mode of Inheritance of ornithine transcarbamylase deficiency was studied in four kindreds, each containing one or more affected children with ammonia intoxication. In two families a total of eight males died in the neonatal period, three of whom had virtually complete absence of activity of this hepatic enzyme. Three families contained female probands with partial deficiency whose hyperammonemia was controlled by dietary protein restriction. All the fathers of affected children had normal activity whereas two mothers had partial deficiency. No such deficiency could be documented in the other two mothers, each with only a single affected female child. On the basis of this study and a genetic analysis of previously reported families, ornithine transcarbamylase deficiency is believed to be inherited as an X-linked dominant trait leading to lethal neonatal hyperammonemia in affected hemizygous males and partial enzyme deficiency with variable severity of hyperammonemia in affected heterozygous females.