X-linkage of Steroid Sulphatase in the Mouse is Evidence for a Functional Y-linked Allele

In the human there is an X-linked gene affecting steroid sulphatase (STS) activity which, when deficient, is associated with X-linked congenital ichthyosis. The gene (STS) is located on the distal tip of the short arm and is only partially inactivated when it is on the inactive X-chromosome. In the mouse, the genetics of STS are not clear; the results of one study using XX:X0 oocyte comparisons indicated X-linkage, but three other studies using STS variants have produced segregation data compatible with autosomal linkage of murine STS. Here we present the results of STS assays of crosses of deficient C3H/An male mice to normal X0 animals which demonstrate X-linkage of STS in the mouse and indirectly indicate the existence of a functional STS allele on the Y-chromosome which undergoes obligatory recombination during meiosis with the X-linked allele.