XY gonadal dysgenesis

XY Gonadal Dysgenesis

The SRY protein, crucial for male sex determination.

XY gonadal dysgenesis, also known as Swyer syndrome, is a type of disorder of sex development (DSD) characterized by the presence of a 46,XY karyotype in an individual with female external genitalia and non-functional gonads. This condition is a form of gonadal dysgenesis, where the gonads are present as "streak gonads" rather than functional ovaries or testes.

Pathophysiology

XY gonadal dysgenesis occurs due to mutations or deletions in genes involved in the development of the testes. The most common gene implicated is the SRY (Sex-determining Region Y) gene, which is located on the Y chromosome. The SRY gene is responsible for initiating the development of the testes from the bipotential gonad.

In individuals with XY gonadal dysgenesis, the SRY gene may be absent or non-functional, leading to the failure of testicular development. As a result, the Müllerian ducts do not regress, and the individual develops female internal genitalia, such as a uterus and fallopian tubes.

Clinical Presentation

Individuals with XY gonadal dysgenesis typically present with primary amenorrhea and lack of secondary sexual characteristics during adolescence. They have a female phenotype with normal female external genitalia but lack functional gonads, leading to infertility.

Diagnosis

Diagnosis of XY gonadal dysgenesis is based on clinical evaluation, hormonal assays, and karyotyping. A 46,XY karyotype in an individual with female external genitalia and streak gonads confirms the diagnosis. Hormonal tests typically show low levels of estrogen and elevated levels of gonadotropins due to the lack of functional gonads.

Management

Management of XY gonadal dysgenesis involves hormone replacement therapy to induce the development of secondary sexual characteristics and maintain bone health. Surgical removal of streak gonads is recommended to prevent the risk of gonadoblastoma, a type of tumor that can develop in dysgenetic gonads.

Related Pages

• Disorder of sex development
• Karyotype
• SRY
• Gonadal dysgenesis
• Amenorrhea