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SRY gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SRY gene

The SRY gene, located on the Y chromosome, acts as a master switch to initiate male sex development in a fetus.

Normal Function

The SRY gene provides instructions for making a protein called the sex-determining region Y protein. This protein is involved in male-typical sex development. The SRY gene is found on the Y chromosome. The protein produced from this gene acts as a transcription factor, meaning it attaches to specific regions of DNA and helps control the activity of particular genes. This protein starts processes that cause a fetus to develop male gonads (testes) and prevents the development of female reproductive structures (uterus and fallopian tubes).

Health Conditions Related to Genetic Changes

Swyer syndrome

Variants in the SRY gene have been identified in approximately 15 percent of individuals with Swyer syndrome (46,XY complete gonadal dysgenesis). Individuals with this condition have a male-typical chromosome pattern (46,XY) but develop female-typical sex characteristics. These variants prevent the production of the sex-determining region Y protein or result in a nonfunctioning protein, meaning the fetus will not develop testes but will develop a uterus and fallopian tubes.

46,XX testicular difference of sex development

Changes affecting the SRY gene can cause 46,XX testicular difference of sex development. Individuals with this condition have a female-typical chromosome pattern (46,XX) but develop male sex characteristics, including testes. This is usually caused by an abnormal exchange of genetic material (translocation) where the SRY gene is misplaced from the Y chromosome onto an X chromosome during the formation of sperm cells.

Other disorders

  • 46,XY difference of sex development: Variants that impair the function of the sex-determining region Y protein can lead to external genitalia that do not look clearly male or clearly female.
  • Ovotesticular difference of sex development: Translocations that misplace the SRY gene onto an X chromosome cause about 10 percent of these cases, where individuals have a 46,XX pattern but possess tissue from both female and male reproductive organs.

Frequently Asked Questions

Testing usually involves a blood sample for DNA extraction followed by PCR or sequencing to detect the presence, absence, or mutations of the SRY gene. Results help determine if a Y chromosome material is present and guide diagnosis and management decisions.
Translocation of SRY to an X chromosome often leads to male development despite a 46,XX karyotype, but the testes are usually dysgenic, resulting in reduced sperm production or infertility. Assisted reproductive technologies may be considered, but success rates are low.
Isolated SRY mutations primarily affect sex development; they are not directly linked to increased cancer risk. However, individuals with gonadal dysgenesis may have a higher risk of gonadal tumors, so regular monitoring and prophylactic gonadectomy are often recommended.
Diagnosis combines clinical features (female phenotype, lack of puberty), hormonal labs (low estrogen, high gonadotropins), imaging (absence of ovaries), karyotype (46,XY), and SRY sequencing. Treatment includes estrogen replacement to induce secondary sexual characteristics, hormone therapy for bone health, and removal of streak gonads to prevent tumor development.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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