H-Y Antigen Gene

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  1. The H-Y antigen gene is found only on the Y chromosome, so it is present only in males.

  2. This gene controls the production of a protein called H-Y antigen.

  3. The H-Y antigen is a type of minor histocompatibility antigen, which means it plays a role in how the immune system recognises tissues.

  4. It is found on the surface of male body cells, including cells in the testes.

  5. Since only males have the Y chromosome, only male cells produce H-Y antigen.

Function of H-Y Antigen:

  1. One of the most important roles of H-Y antigen is in sexual development.

  2. During the early development of a male embryo, the presence of the H-Y antigen helps trigger the development of the testes.

  3. The testes then start producing testosterone, which helps in forming the male body structure.

  4. So, the H-Y antigen is one of the early signals for the body to develop as male.

  5. Without this antigen, even if the child has an XY pair, male development might not occur properly.

H-Y Antigen and Organ Transplant:

  1. The H-Y antigen is important in organ and tissue transplantation.

  2. If an organ from a male (with H-Y antigen) is transplanted into a female (who lacks H-Y antigen), the female's immune system may reject the organ.

  3. This is because the female body recognises the H-Y antigen as foreign and attacks it.

  4. This immune response is called H-Y incompatibility.

  5. That’s why doctors are very careful when matching organs for transplants between male and female donors.

Why is the H-Y Antigen Gene Sex-linked?

  1. It is completely Y-linked because it is found only on the non-homologous region of the Y chromosome.

  2. Since there is no matching gene on the X chromosome, females do not carry or pass on this gene.

  3. The gene is inherited only from father to son, because only males pass on the Y chromosome.

  4. This is a clear example of complete sex linkage, where the gene is strictly limited to one sex.

Medical Importance:

  1. Researchers also study the H-Y antigen in relation to male infertility and immune system disorders.

  2. It may help in understanding why some pregnancies with male embryos are lost due to immune rejection.

  3. It is also being studied in cancer research, especially in testicular cancers.

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