DNA analysis of ornithine transcarbamylase deficiency.

By analysing the restriction fragment length polymorphism (RFLP) detected by an ornithinetranscarbamylase (OTC) gene specific DNA probe, we followed the segregation of the defective gene in two families with OTC deficiency (X-linked disease). We were able to exclude some female family members as carriers. In one case a doubtful result obtained in a biochemical carrier detection test (by examining the renal orotic acid excretion after a protein load) could be clarified by DNA analysis. In every family with OTC deficiency, carrier detection should be biochemical with additional DNA analysis. Previous results of the biochemical carrier test should be controlled by DNA analysis, especially when "normal" results were obtained.