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A Single Mutation Acts as a Molecular Switch for Sex Determination
The gender symbols of a female and male.

In humans, sex determination is normally regulated by the inheritance of specific chromosomes, with females inheriting two X chromosomes and males inheriting and an X and a Y chromosome. The Y chromosome directs formation of the male reproductive system and without a Y chromosome an individual will develop with a female reproductive system. However, genetic defects can occasionally lead to sexual organ development that does not correspond to the chromosomal makeup of an individual.

A research team including members of the Undiagnosed Diseases Network have identified the cause of a subset of these genetic disorders. By sequencing DNA from four different families they were able to show that remarkably a single specific mutation in a single gene (NR5A1) can act as a molecular switch, causing XX individuals to develop as a male and XY individuals to develop as a female. This study highlights the power of sharing genetic data both inside and outside of the UDN in aiding the generation of a diagnosis for rare disorders.


This page last reviewed on August 24, 2023