Hyperammonaemia in 20 families. Biochemical and genetical survey, including investigations in 3 new families.

Archives of Disease in Childhood, 49, 443.Hyperammonaemia in 20 families: biochemical and genetical survey, including Investigations in 3 new families.Investigations have been made in 3 new and 2 previously reported families with ornithine transcarbamylase defects and the results are reported.The biochemical findings relevant to the diagnosis of hyperammonaemia in these and the 15 other families known to be affected are tabulated.In 2 families where the propositus appears to have a variant type of ornithine transcarbamylase defect, the mode of inheritance is uncertain.In the other 18 families, while it cannot be assumed that all affected cases are suffering from the results of an identical mutation, there is good evidence for an X-linked dominant mode of inheritance, and no positive evidence in any family for a different mode of inheritance.