Observations in the Scandinavian wood lemming (Myopus schisticolor), combined with Ohno's law of the evolutionary conservatism of the mammalian X chromosome, suggest the existence in man of an X-linked gene that exercises a regulatory role on histocompatibility Y antigen . The lemming has an excess of phenotypic females because many develop ovaries and mature as fertile females, anatomically indistinguishable from their 'normal' XX sisters (Fredga et al., 1976). Even though the Y chromosome appears to be intact, these females do not synthesize H-Y antigen (Wachtel et al., 1976) The XY female wood lemming has an X-bearing germline and produces only X-bearing germ cells. All its XY sons are of female phenotype like itself. Thus the explanation is not a structural mutation of H-Y, but rather a mutation in an X-borne regulator of H-Y (Fredga et al., 1977). It was suggested that the presumably X-linked XY female gonadal dysgenesis may represent the human homolog. The H-Y antigen is a series of polymers of a hydrophobic polypeptide roughly 160 amino acid residues long (Iwata et al., 1979 and Nagai et al., 1979).
Nucleic acid binding, DNA binding, Transcription factor
Because the mutant phenotype nullifies the repressor action, "female" lemmings are fertile with normal ovaries. This is different from the human homolog (Turner's women).
Expression regulated by
Oocyte, Cumulus, Granulosa, Theca, Luteal cells
Mutation name: female gonadal dysgenesis
type: None fertility: infertile - ovarian defect Comment: That the human has infertility and 'streak gonads' may not be a fundamental difference, inasmuch as the XO rodent, unlike the Turner syndrome human, is fertile with normal ovaries.