ABSTRACT
The sparse-fur mutation arose spontaneously in the progeny of an irradiated male at the Oak Ridge National Laboratory. The abnormal skin and hair mutation arose spontaneously in a stock of mice at Purdue University and was found to closely resemble sparse-fur. The sparse-fur and abnormal skin and hair mutations failed to complement; that is, female mice doubly heterozygous for the two mutations phenotypically resembled either homozygote. Mutant forms of the enzyme have been described in sparse-fur and in abnormal skin and hair mice. Livers of hemizygous abnormal skin and hair mice synthesize two distinct ornithine transcarbamylase precursor polypeptides; one is normal in size, and the second is elongated. Sparse-fur and abnormal skin and hair mutations resemble two different subsets of human ornithine transcarbamylase deficiencies. Both the sparse-fur and abnormal skin and hair mutations have been used extensively to characterize the basis of the comparable human disease.
