Sun Feb 09 21:33:00 UTC 2025: **Rare Genetic Cases Challenge Understanding of Sex Determination**
**CHENNAI, INDIA – February 10, 2025** – Two recent studies have revealed exceptional cases of biological females possessing the SRY gene, the primary trigger for male sex development, challenging conventional understanding of sex determination. Researchers from the Renato Dulbecco University Hospital in Italy and Cincinnati Children’s Hospital Medical Center in the USA reported their findings in *Genes* and *Molecular Genetics and Genomic Medicine*, respectively.
The SRY gene, located on the Y chromosome, typically initiates male development. However, these studies identified instances where the SRY gene translocated to the X chromosome, resulting in XX individuals with the SRY gene. Surprisingly, these individuals developed into healthy biological females.
The key to understanding these exceptional cases appears to be the simultaneous deletion of a small portion of the X chromosome during translocation. This deletion, absent in previously reported cases of XX individuals with the SRY gene who developed as infertile males, resulted in biased X chromosome inactivation. The X chromosome containing the translocated SRY gene was preferentially inactivated, silencing the SRY gene and allowing for female development.
While most cases of XX individuals with the SRY gene result in infertile males, these exceptional findings highlight the complexity of sex determination and the potential impact of seemingly small genetic variations. The researchers emphasize the need for long-term follow-up studies to assess the potential for late-onset sex development disorders in these individuals. The discovery also suggests the need to analyze available genome sequences of biological females for the presence of similar cryptic SRY-bearing translocations to improve genetic counseling. The studies underscore the importance of considering associated gene deletions in interpreting genetic anomalies.
First Piper 