H-Y antigen

H-Y antigen is a male tissue specific antigen.[1] Originally thought to trigger the formation of testes, it is now known that it doesn't trigger the formation of testes but may be activated by the formation of testes.[2] In its production, there are at least two loci involved, an autosomal gene that generates the antigen and one that generates the receptor.[3]

The H-Y antigen secreted by the testis is identical to müllerian-inhibiting substance.[1]

Association with spermatogenesis

It has been shown that male mice lacking in the H-Y antigen, hence lacking in the gene producing it, have also lost genetic information responsible for spermatogenesis.[4] This result also identified a gene on the mouse Y chromosome, distinct from the testis-determining gene, that was essential for spermatogenesis, thus raising the possibility that the very product of this "spermatogenesis gene" is the H-Y antigen.[4]

Male homosexuality and the birth order effect

Among humans, it has been observed that men with more older brothers tend to have a higher chance of being homosexual - in fact, for every additional older brother, a man's chance of being homosexual can rise by up to 33%.[5] One theory to explain this involves H-Y antigens, which suggests that a maternal immune reaction to these antigens has, to an extent, an inhibitory effect on the masculinization of the brain, and therefore, the more male foetuses that the mother of a man has had, the greater the maternal immune response towards him[6] and thus the greater the inhibitory effect on brain masculinization, which is believed to be a factor in sexual orientation.[5] This hypothesis is supported by evidence that older sisters have no discernible influence on the sexual orientation of later-born males, which would be expected since H-Y antigen is male tissue specific, the 'probable involvement of H-Y antigen in the development of sex-typical traits, and the detrimental effects of immunization of female mice to H-Y antigen on the reproductive performance of subsequent male offspring'.[7]

References

  1. 1 2 Müller U, H-Y antigens - Hum Genet. 1996 Jun;97(6):701-4.
  2. ↑ Wolf U, The serologically detected H-Y antigen revisited - Cytogenet Cell Genet. 1998;80(1-4):232-5.
  3. ↑ H-Y Antigen -- Medical Definition
  4. 1 2 Burgoyne P S, Levy E R, McLaren A Spermatogenic failure in male mice lacking H-Y antigen - Nature. 1986 Mar 13-19;320(6058):170-2.
  5. 1 2 Ridley, M. 2000. Genome: The Autobiography of a Species in 23 Chapters. Harper and Collins.
  6. ↑ Vaccination and immunity for iGCSE Biology - YouTube
  7. ↑ Blanchard R, Klassen P H-Y antigen and homosexuality in men - J Theor Biol. 1997 Apr 7;185(3):373-8.


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