Swyer syndrome

Swyer syndrome

: A person is born without functional gonads and known as XY gonadal dysgenesis.

:is a condition in which individuals with one X chromosome and one Y chromosome in each cell, the pattern normally found in males, have a female appearance. 

People with this disorder have female external genitalia and a normal uterus and Fallopian tubes. However, they do not have functional gonads (ovaries or testes). 

Their gonads are minimally developed clumps of tissue present instead testes or ovaries.

This kind of gonad in swyer syndrome are known as gonadal streaks. These abnormal gonads often become cancerous, so they are usually removed surgically early in life.

Causes:

1)    Mutations in the SRY gene (15 % to 20 %): prevent production of the sex-determining region Y protein or result in the production of a nonfunctioning protein. This fetus will develop as a female despite having a Y chromosome.

2)     Mutations in the NR5A1 and DHH genes (small number): The NR5A1 gene produce transcription factor steroidogenic factor 1 that help to produce sex hormones and development of male sexual characteristics. The DHH gene produce a member of the hedgehog protein family. Hedgehog proteins are important for early development in many parts of the body. Mutations in the NR5A1 and DHH genes impair the process of male sexual differentiation, causing to develop a female appearance despite having a Y chromosome.

3)     Changing in the NR0B1 gene (small number): The NR0B1 gene provides a DAX1 protein that have important role in the development and function of gonads. A duplication of a region in the X chromosome can result in an extra copy of the NR0B1 gene, which leads to the production of extra DAX1 protein. Before birth, an excess of DAX1 protein prevents the formation of male reproductive tissues, including the testes and male external genitalia.

These people are typically raised as females and have a female gender identity.

Treatment: hormone replacement therapy during adolescence to induce menstruation and development of female secondary sex characteristics such as breast enlargement and body hair.

http://www.webmd.com/a-to-z-guides/swyer-syndrome

http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/1204/viewAbstract