SRY

Overview
SRY (Sex-determining Region Y) is a sex-determining gene on the Y chromosome in humans and other primates.

The SRY gene encodes the testis determining factor, which is also referred to as the SRY protein.

Impact upon anatomical sex
Since its discovery, the importance of the SRY gene in sex determination has been extensively documented:
 * Humans with one Y chromosome and multiple X chromosomes (XXY, XXXY etc.) are usually males.
 * Individuals with a male phenotype and an XX (female) genotype have been observed; these males have the SRY gene in one or both X chromosomes, moved there by chromosomal translocation. (However, these males are infertile.)
 * Similarly, there are females with an XXY or XY genotype. These females have no SRY gene in their Y chromosome, or the SRY gene exists but is defective (mutated).

SRY and the Olympics
One of the most controversial uses of this discovery was as a means for gender verification at the Olympic Games, under a system implemented by the International Olympic Committee in 1992. Athletes with a SRY gene were not permitted to participate as females, although all athletes in whom this was "detected" at the 1996 Summer Olympics were ruled false positives and were not disqualified. In the late 1990s, a number of relevant professional societies in United States called for elimination of gender verification, including the American Medical Association, the American Academy of Pediatrics, the American College of Physicians, the American College of Obstetricians and Gynecologists, the Endocrine Society and the American Society of Human Genetics, stating that the method used was uncertain and ineffective. The screening was eliminated as of the 2000 Summer Olympics.

SRY-related diseases and defects
Individuals with XY genotype and functional SRY gene can have a female phenotype, where the underlying cause is androgen insensitivity syndrome (AIS).

SRY has been linked to the fact that men are more likely than women to develop dopamine-related diseases such as schizophrenia and Parkinson's disease. SRY makes a protein that controls concentrations of dopamine, the neurotransmitter that carries signals from the brain that control movement and coordination.