Assignment of the h-y antigen gene to the short arm of chromosome y

Histocompatibility y antigen (h-y) or y factor, a male-specific antigen, was first noted by Eichwald and Silmser4 who observed in 1955 that when females were challenged with intrastrain or syngenic male grafts, their reaction against this antigen often resulted in the destruction of the graft. Serological determination of the H-Y antigen on mouse sperm has been detected using a cytotoxicity test system7. With the use of this test the H-Y antigen has been investigated and has been implicated in sex determination6,9,10,13,15. The indication that a genetic determinant for the H-Y antigen is located on the Y chromosome was presented in Bunker’s report1, which showed that testicular teratomas that retain the Y chromosome expressed the H-Y antigen. Only teratoma cells lacking the chromosome were accepted when transplanted to sensitized syngenic females. If the structural or regulatory gene of the H-Y antigen is on the Y chromosome, then all animals lacking this chromosome should fail to express the antigen. It has been noted, however, that in XX mice, the XX human male, and the human XX true hermaphrodite, testes are present and the tissues are H-Y antigen positive12. This information might be taken as support for an autosomal location for the H-Y gene, but it cannot be ruled out that a piece of the Y chromosome too small to be seen cytogenetically could have been translocated to the X chromosome, as hypothesized by Ferguson-Smith5. Rary, et al.11 reported a case in which an isochromosome for the long arm of the Y[46, X, i(Yq)] was determined to be H-Y antigen negative, and Koo, et al. have recently confirmed that observation in another individual with an isochromosome for the long arm of the Y chromosome. However, Koo, et al.8 also have reported an H-Y antigen positive case, in which most of the long arm of the Y chromosome was translocated to the X chromosome, with the short arm of the Y and the centromere apparently missing. This finding is contradictory to the two previous reports of no H-Y antigen in cells from individuals with an isochromosome for the long arm of the Y. Again, however, the possibility of a translocation of the short arm of the Y to another chromosome has not been ruled out in this particular case. In this paper we record the H-Y antigen to be present in one individual with a 46, X, i(Yp) karyotype, and absent in another individual with a 46, X, i(Yq) karyotype.