Swyer Syndrome Explained (And What It Means For Your Health)

According to the National Organization for Rare Disorders (NORD), Swyer syndrome, which was first described by a London endocrinologist named Dr. Gim Swyer in 1955, is a rare disorder in which the reproductive glands fail to develop. Girls with Swyer syndrome have the same sex chromosomes as boys (XY), but they are female as far as their physical appearance and they have a vagina, uterus, and fallopian tubes. Girls with this sexual development disorder do not have ovaries, however. Instead, they have what are known as "gonadal streaks." This fibrous tissue is not able to produce the female sex hormones so girls with Swyer syndrome will not go through puberty without hormone replacement therapy (HRT).

Cleveland Clinic states that it is not known exactly what causes Swyer syndrome. However, it is thought that any genetic mutation that alters testicular development could potentially cause it. In some cases, the genetic mutation can be inherited from a parent, but others may develop a genetic mutation for no known reason. In about 15% to 20% of cases, there is a mutation of the SRY (sex-determining region Y) gene. Mutations in MAP3K1, DHH, or NR5A1 might also be responsible.

Swyer syndrome can have several important implications for women's health. This is primarily due to the absence of normal ovaries and the associated lack of female sex hormones.

MedlinePlus explains that because children with Swyer syndrome appear female, they tend to be raised as female and identify as such. However, since they do not produce sex hormones, they will not go through puberty unless they receive treatment with the sex hormones estrogen and progesterone. If they do receive HRT, however, it is possible for them to go through puberty and develop breasts. Their uterus will also be able to develop and they can eventually start to have menstrual periods. Additionally, it may be possible for them to become pregnant with a donated egg or embryo.

According to Cleveland Clinic, another important health issue faced by those with Swyer syndrome is weakened bones. When girls do not receive HRT, it can cause their bones to develop osteopenia (reduced bone density) and osteoporosis (brittle bones). However, HRT can help prevent bone loss.

Additionally, Cleveland Clinic writes that about 30% of people with Swyer syndrome may develop a tumor in the area of the gonadal streaks. Gonadoblastoma is the most common type.

Osmosis explains that Swyer syndrome is often not diagnosed until girls are in their teens when they are late going through puberty and still haven't gotten their period. To arrive at a diagnosis, a doctor will consider the girl's medical history, the presence of tell-tale symptoms such as a lack of a period, and their test results. They might also order imaging to help visualize the internal reproductive organs. A diagnostic laparoscopy might also be done in order to provide a better view of the internal anatomy. Chromosomal analysis can confirm the diagnosis. Genetic testing can be done to determine the specific genetic mutation that is responsible for the patient's condition.

HRT and surgical removal of the gonadal streaks are the standard treatments, per NORD. While gonadoblastoma is benign, it is believed to be a precursor to malignancy so doctors will generally recommend removing these growths. NORD also notes that people with SF1 mutations may have adrenal insufficiency which requires treatment. They further recommend genetic counseling for the patient and the family. Additionally, women who wish to have children may consider the use of in vitro fertilization with donor eggs in order to become pregnant.