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Swyer syndrome
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Swyer syndrome

Swyer syndrome, or XY gonadal dysgenesis, is a type of gonadal dysgenesis marked by the inability of a genetic male to develop testes. Individuals with this syndrome develop the normal primary sexual characteristics of females, including a uterus and vagina, but the ovaries remain as undeveloped "streak gonads". The condition is not apparent at birth, as individuals with the condition appear as normal females; symptoms most commonly appear during puberty when the absence of breast enlargement and menstruation raise suspicions of a potential developmental disorder.

Table of contents
1 Overview
2 Symptoms
3 Diagnosis
4 Treatment
5 Prognosis
6 External links


Sexual development is governed in part by genes located on the X and Y chromosomes. In normal XY individuals, these genes cause the fetus to develop the sexual organs of males rather than those of females. But in XY individuals with Swyer syndrome, there is an abnormality in one or more of these genes that prevents normal masculine development, favoring female sexual development instead. Thus these individuals develop all the female primary sexual characteristics except for the ovaries, which are instead composed of fibrous connective tissue, and are unable to produce hormones such as estrogen.


As individuals with Swyer syndrome have normal female genitalia at birth, including a vagina and clitoris, symptoms of the syndrome typically appear in late childhood, when the effects of puberty are minimal or absent altogether. Characteristic symptoms include:

Some individuals with Swyer syndrome also have a slightly enlarged clitoris.


In females with delayed puberty, a pelvic ultrasound can be performed to confirm the presence or absence of ovaries.

Additionally, blood can be taken for a karyogram, which identifies the full set of chromosomes of the female. Females with Swyer syndrome will have both X and Y chromosomes rather than a set of two X chromosomes, which is normal for females.


Symptoms of Swyer syndrome can be treated with hormone replacement therapy (HRT), although surgical procedures are not uncommon. A typical HRT regimen includes estrogen and progesterone treatment to regulate menstruation and induce the female's secondary sexual characteristics. In some cases, the fibrous streak gonads are surgically removed as a precautionary measure against the development of gonadoblastomas, a type of cancer of the gonads.



In the absence of ovaries, ovulation is impossible, and so natural pregnancy is likewise impossible. Pregnancy via implantation of a fertilized ovum is a viable alternative, however, as the uterus and endometrium are intact and sufficient for bringing a pregnancy to term.

External links