Why in the news?
Exceptional instances of females possessing the SRY gene have been reported three times in the medical literature, two in 2024 itself.
- The SRY gene – Provides instructions for making a protein called the sex-determining region Y protein.
- SRY Gene's Role – The SRY gene, located on the Y chromosome, is the primary determinant of maleness.
- Its presence typically leads to the development of male characteristics, while its absence leads to female development.
- Typical Sex Determination – Eggs carry an X chromosome, while sperm carry either an X or a Y.
- XX combinations result in females, and XY combinations result in males.
- SRY Translocations – Rarely, the SRY gene can move from the Y chromosome to an X chromosome (a translocation).
- Sterile male – If this X chromosome fertilizes an egg, the resulting XX individual usually develops as a sterile male, a man who is unable to reproduce due to a lack of sperm or other reproductive issues.
- Exceptional Females with SRY – Cases of fertile females with the SRY gene on an X chromosome are exceptional cases.
- Key to Female Development in These Cases – The key difference in these exceptional females lies in a specific deletion on the X chromosome carrying the SRY gene.
- This deletion results in the inactivation of the translocated X chromosome during female development.
- This "biased" inactivation silences the SRY gene, allowing female development to proceed.
- If the other X chromosome were inactivated, the individual wouldn't survive because the deleted genes are essential for life.
- Significance – These cases reinforce the SRY gene's importance in male development.
- Only when it is silenced (through biased X-inactivation due to the deletion) can female development occur even with the SRY gene present.
- Further Research – The article suggests the need for more research to understand the long-term effects of SRY translocations, even when they result in female development.
- It also highlights the potential value of screening for such translocations in the future.
Reference
The Hindu - SRY Gene
