SRY

The SRY gene provides instructions for making a transcription factor called the sex-determining region Y protein. A transcription factor is a protein that attaches (binds) to specific regions of DNA and helps control the activity of particular genes. The sex-determining region Y protein causes a fetus to develop as a male.

People normally have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics. Females have two X chromosomes (46,XX), and males have one X chromosome and one Y chromosome (46,XY). The SRY gene is located on the Y chromosome.

Swyer syndrome - caused by mutations in the SRY gene

Mutations in the SRY gene have been identified in between 15 percent and 20 percent of individuals with Swyer syndrome, also known as 46,XY complete or pure gonadal dysgenesis. SRY mutations that cause Swyer syndrome prevent production of the sex-determining region Y protein or result in the production of a nonfunctioning protein. A fetus whose cells do not produce functional sex-determining region Y protein will develop as a female despite having a Y chromosome.

46,XX testicular disorder of sex development - associated with the SRY gene

In most individuals with 46,XX testicular disorder of sex development, the condition results from an abnormal exchange of genetic material between chromosomes (translocation). This exchange occurs as a random event during the formation of sperm cells in the affected person's father. The SRY gene is misplaced in this disorder, almost always onto an X chromosome. A fetus with an X chromosome that carries the SRY gene will develop male characteristics despite not having a Y chromosome.

other disorders - associated with the SRY gene

SRY mutations that impair but do not eliminate the function of the sex-determining region Y protein have been identified in a small number of people with 46,XY disorder of sex development, or partial gonadal dysgenesis. Affected individuals may have external genitalia that do not look clearly male or clearly female (ambiguous genitalia) or other abnormalities of the genitals and reproductive organs.

About 10 percent of individuals who have both testicular and ovarian tissue, a condition called ovotesticular disorder of sex development, have two X chromosomes with one carrying the SRY gene.