Swyer syndrome is a rare condition in which a person is born with XY chromosomes, the combination usually associated with males, but their reproductive organs develop along a typically female pattern. The person typically has female external anatomy and a uterus and fallopian tubes.
The condition often goes unnoticed during childhood and comes to light during adolescence, when puberty does not progress normally or menstruation does not begin. It can also be diagnosed later during investigations for infertility. Here’s all you need to know about Swyer syndrome. The person generally develops female external genitalia, while the uterus and fallopian tubes are usually present.
Swyer syndrome is a rare difference of sex development, medically known as 46,XY complete gonadal dysgenesis. A person with the condition has a 46,XY chromosome pattern, but the gonads do not develop into functioning testes, according to the US’ Genetic and Rare Diseases Information Center. The condition is estimated to occur in about one in 80,000 people,
Instead, they remain as small, non-functioning structures called “streak gonads”.
Delayed or incomplete development of secondary sexual characteristics can also prompt investigation. The condition can sometimes remain undiagnosed even when a person reaches adulthood. Genetic testing can be used to investigate the underlying cause, including variants in SRY and other genes involved in gonadal development. However, not finding an SRY mutation does not exclude Swyer syndrome. In some patients, even more extensive genetic testing may not identify the precise molecular cause. However, the effects of Swyer syndrome can be effectively managed. Hormone replacement therapy, usually involving oestrogen and subsequently an appropriate progestogen regimen when indicated, is used to induce and maintain puberty, support development of secondary sexual characteristics and protect bone health. Fertility is another important consideration. However, if the uterus is present and sufficiently developed, pregnancy can be possible through IVF using a donated egg or embryo. Research shows that patients with Swyer syndrome can have successful pregnancies following endometrial preparation with hormones and IVF using donated eggs. Following pregnancy and delivery, continued hormone replacement is important for maintaining bone health. In other words, Swyer syndrome itself cannot currently be reversed, but its effects can be managed. Hormone replacement can address the absence of normal gonadal hormones, removal of the streak gonads can reduce the risk of tumours, and assisted reproductive techniques can make pregnancy possible for some patients.
Because the streak gonads do not produce sufficient sex hormones, spontaneous breast development may be limited. Because the streak gonads cannot produce eggs, people with Swyer syndrome cannot conceive using their own eggs. There is currently no treatment that can change the 46,XY chromosome pattern or turn the streak gonads into functioning ovaries.
