The result of the present study and results of previous studies suggest that genes for ornithine transcarbamylase (OTC), DMD, and GK and putative genes responsible for congenital adrenal hypoplasia (AHC) and GTD are arranged from telomere to centromere as pter--GTD--AHC--GK--DMD--OTC--cen.
These sequences map provocatively close to the mdx mutation and unexpectedly distant from sparse fur, spf, the mouse homologue of OTC (ornithine transcarbamylase) which is closely linked to DMD on the human X chromosome.
OTC is located more closely to the Duchenne muscular dystrophy mutation than previously reported markers such as RC8 and L1.28, and therefore should prove useful in carrier detection and haplotype analysis of families carrying the mutation causing the disease.
The ornithine transcarbamylase gene and four anonymous DNA sequences map within band Xp21, flanking the presumed locus for Duchenne muscular dystrophy.
Two DNA markers, a random DNA fragment 754 and the cDNA sequence encoding the gene for ornithine transcarbamylase (OTC) have been studied in kindreds segregating for Duchenne muscular dystrophy.
Because the gene maps near the Duchenne muscular dystrophy locus, the ornithine transcarbamylase probe may be useful in carrier detection and prenatal diagnosis of Duchenne muscular dystrophy as well as of ornithine transcarbamylase deficiency.