H-Y antigen in X,i(Xq) gonadal dysgenesis: evidence of X-linked genes in testicular differentiation

Diagnostic applications of H-Y serology: H-Y negative phenotype in cells from 45,X/46,XY fetus with testes

Sexual dysmorphism should be considered likely in cases in which H-Y- phenotype and XY complement are found together. In the case described here, a pregnancy was terminated at nineteen weeks of gestation after 45,X and 46,XY cell lines were detected among cultured amniocytes. The fetus was a male with hypospadias and intraabdominal testes containing irregular tubules and hyperplastic interstitium. Cultured skin fibroblasts, containing 45,X and 46,XY lines in ratio of 18:2, were typed H-Y antigen negative. This underscores the danger of predicting gonadal type on the basis of somatic H-Y phenotype.

Serologically H-Y antigen-negative XO mice

In a series of six independent experiments organ homogenates of 35 mice of the XX, XO or XY sex chromosome constitutions were absorbed using three different anti-H-Y antisera raised in inbred female LEW rats. Residual activities of absorbed antisera were tested in the Raji cell, complement-dependent, cytotoxicity test. Homogenates of various tissues, including the gonads, of XX and XO females were equally unable to absorb H-Y antibodies, indicating that tissues of these mice do not carry the H-Y antigen. In contrast, XY male homogenates fully absorbed H-Y antibodies of antisera at concentrations of 1/2 to 1/4. We discuss our findings with special attention to the problem of the existence of one or more H-Y antigens and, to the genetic regulation of the expression of this antigen.

Hae III restriction of DNA from three cases with nonfluorescent Y chromosomes (45XO/46XYnf)

Hae III restriction patterns are reported in three cases with normal-sized but nonfluorescent Y chromosomes (XO/XYnf mosaics). The 3.4- and 2.1-kb fragment classes of reiterated Y chromosomal DNA were not present in the three cases. Mechanisms leading to these findings are discussed.

Variability in serologically detected male antigen titer and some resulting problems: a critical review

Seroologically detected male antigen" (also called H-Y antigen) was first described in normal male mammals but now appears to occur in normal female mammals as well. "Serologically detected male predominant" (SDMP) antigen is a more appropriate name since the titer in normal males usually exceeds that of normal females. As we show, in each sex there is a considerable inter-individual variability in SDMP antigen titer, and in moderate-to-large size samples the low end of the male range of titers usually coincides with the high end of the female range. Several major problems arise from failure to recognize and/or to deal adequately with this normal variation in SDMP antigen titer. The chief problem is that the "controls" used (often a single individual) may be inadequate and misleading, leading to unjustified designation of samples as "positive", "negative", or even "deviant" ("intermediate", "reduced") for SDMP antigen titer. Other problems include deficiencies in technique and lack of statistical control for test and sample variability. Adequate attention to these problems, especially to the normal variability in SDMP antigen titer, could reduce the contradictions and inconsistencies which have troubled this field.

Presence of H-Y antigen in female patients with sex-chromosome mosaics and absence of testicular tissue

H-Y antigen was tested in five women with sex chromosome mosaicism and gonadal streaks. Three patients had a 45,X/46,XY or 46,X,der(Y) and two a 45,X/46,X, der(X) chromosome constitution. All patients were H-Y antigen positive. Lack of testis differentiation in these women may be explained by subthreshold expression of H-Y antigen, different H-Y antigen molecules, and/or different tissue distribution of the chromosome mosaicism.

The H-Y antigen and its functions: a review and a hypothesis

Having reviewed the status of H-Y as the sex-determining antigen concerned with the differentiation of the dominant gonad, we consider some of the problems deriving from the tests for this antigen, and from their application to the study of natural experiments. To reconcile the results of these studies with the alleged influence of H-Y on gonadal development, we propose and discuss a hypothesis on the genetic control of the synthesis of this antigen. This states that an autosomally-coded, positively cross-reacting precursor is rendered biologically active by a Y-chromosomal gene, and transformed (in a dose-dependent manner) into a biologically inactive, antigenically negative substance under the influence of an X-chromosomal gene.

H-Y antigen expression in patients with X-autosomal translocations and gonadal dysgenesis

Cells from three patients with early gonadal failure and a balanced reciprocal translocation involving the long arm of the X chromosome and an autosome were studied. Fibroblasts from a patient with a similar balanced reciprocal translocation but normal reproductive capabilities were also studied. Two of the four patients were found to have serologically detectable H-Y antigen on their cells. Since H-Y antigen has been found on the cells of other patients with X chromosome abnormalities but without a Y chromosome, it is thought that the X chromosome plays a role in the regulation of H-Y antigen expression. This study suggests that the long arm of the X chromosome may be involved but the location of a regulatory gene cannot be identified in these studies. These cases do not permit us to implicate H-Y antigen as a cause of gonadal dysgenesis and early gonadal failure in females who have structurally abnormal X chromosomes.

Correlation between the number of sex chromosomes and the H-Y antigen titer

H-Y antigen was studied serologically on blood cells and cultured fibroblasts of patients with numerical aberrations of the sex chromosomes. As compared with normal males, patients with the karyotypes 48,XXXY and 49,XXXXY have reduced H-Y antigen titers; a tendency toward reduced titers can also be detected in the 47,XXY Klinefelter syndrome. The existence of an intermediary titer was further substantiated by a quantitative absorption test applied to cells with the 49,XXXXY karyotype. It appears that in the presence of one Y chromosome, the H-Y antigen titer decreases with an increasing number of X chromosomes. In contrast, the H-Y antigen titer is increased if, at a given number of X chromosomes, the number of Y chromosomes is increased, as in the 47,XYY male. Consequently, patients with 48,XXYY chromosomes are in the male control range. The findings are interpreted under the hypothesis of a controlling or modifying influence of the sex chromosomes on the titer of H-Y antigen.

X-linked genes of the H-Y antigen system in the wood lemming (Myopus schisticolor)

H-Y antigen was investigated in 18 specimens representing six different sex chromosome constitutions of the wood lemming (Myopus schisticolor). The control range of H-Y antigen was defined by the sex difference between normal XX females (H-Y negative per definitionem) and normal XY males (H-Y positive, full titer). H-Y antigen titers of the X*Y and X*0 females were in the male control range, while in the X*X and X0 females the titers were intermediary. Data were obtained with two different H-Y antigen assays: the Raji cell cytotoxicity test and the peroxidase-antiperoxidase (PAP) method. Fibroblasts, gonadal cells, and spleen cells were checked. Presence of full titers of H-Y antigen in the absence of testis differentiation is readily explained by the assumption of a deficiency of the gonad-specific receptor of H-Y antigen. Since sex reversal is inherited as an X-linked trait, genes for this receptor are most likely X-linked. The implications of our findings are discussed in connection with earlier findings concerning H-Y antigen in XY gonadal dysgenesis in man and the X0 situation in man and mouse.

Presence of H-Y antigen in patients with Ullrich-Turner syndrome and X-chromosome rearrangements

Cells from eight of ten patients with gonadal dysgenesis and an isochromosome for the long arm of X, (i(Xq)), have been found to be H-Y antigen-positive, using an assay that employs rat antiserum and Raji cells. In addition, two patients with del(Xq) were also found to be H-Y antigen-positive, whereas four patients in whom only a 45,X line was detected were H-Y antigen-negative. These findings suggest that the X chromosome plays a role in the expression of H-Y antigen in the absence of a Y chromosome. Since our patients with i(Xq) show no evidence of testicular differentiation, it is clear that there is not enough H-Y antigen on these patients' cells to direct the development of a testis. These findings are consistent with the view that the normal functioning of genes on the X and the Y chromosomes is necessary for testicular organogenesis to occur.