PATCHY FUR (PAF), A SEMIDOMINANT X-LINKED GENE ASSOCIATED WITH A HIGH-LEVEL OF X-Y NONDISJUNCTION IN MALE-MICE

Several X-linked mutations that have associated sex chromosomal nondisjunction have been identified in the mouse. We describe a new semidominant X-linked mutation called patchy fur (Paf) that produces an abnormal coat. It maps to the distal end of the murine X chromosome very near the XY pseudoautosomal region. The degree of severity in affected mice is hemizygous males > homozygous females > heterozygous females. An unusual feature of Paf is that either the mutation itself or an inseparable chromosomal abnormality causes delayed disjunction of the X and Y chromosomes at meiotic metaphase I, which in turn results in approximately 19% XO progeny and slightly less than 1% XXY progeny from Pat/Y males. The effect occurs only in male carriers and thus must extend into the proximal end of the XV pairing region. © 1990 The American Genetic Association.