OTC and ornithine carbamoyltransferase deficiency: Making use of this phenomenon, in the present paper we have explored the feasibility of selecting fibroblast clones from a heterozygous OTC female, having spontaneously silenced one of the X chromosomes (either the paternal or the maternal), differentiated to hepatocytes phenotypically expressing the wild type or the deficient OTC gene, and recapitulating OTCD in mice transplanted with the mutant cells.