Prenatal exclusion of ornithine transcarbamylase deficiency by direct gene analysis

Direct gene analysis was used in the prenatal exclusion of ornithine transcarbamylase (OTC) deficiency; karyotyping the family's previously affected child had already identified the defect as a small deletion. A cloned OTC gene and two other X chromosome-specific probes were mixed, and hybridised to fetal DNA obtained from cultured amniocytes; the fetus was shown to be a normal male.