Gene for OTC: characterisation and linkage to Duchenne muscular dystrophy

Cloned coding sequences for rat and human ornithine transcarbamylase (OTC) were obtained by screening a rat and a human cDNA library respectively with a synthetic oligonucleotide corresponding to 27 bases of the rat sequence. These clones, 1100 bp long for the rat clone and 1300 bp for the human, contain approximately 80% of the human OTC coding sequence. The OTC mRNA length determined by Northern blot analysis is 1700bp. The human OTC sequence was shown to be localised Xp11.4-Xp21 using somatic cell hybrids. There is a frequent RFLP revealed with the restriction enzyme MspI. 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.