In 2 females with OTC deficiency, we also found 2 large heterozygous deletions of approximately 7.4 Mb and 9 Mb on the short arm of the X chromosome extending from sequences telomeric to the DMD gene [dystrophin (muscular dystrophy, Duchenne and Becker types)] to sequences within or centromeric to the OTC gene (ornithine carbamoyltransferase).