Swyer syndrome

Swyer syndrome

Description, Causes and Risk Factors:

Swyer syndrome is also knowns as gonadal dysgenesis is characterized by "streak gonads" is a phenotypic female with a 46,XY karyotype. This condition is due to a mutation which inhibits the function of the Y-borne determinant that would normally cause the indifferent embryonic gonad to differentiate into a testis. The streak gonad is incapable of ovulation or estrogen secretion. The syndrome is sometimes called "pure gonadal dysgenesis," however, this designation may also refer to the presence of streak gonads with a 46,XX karyotype. Mixed gonadal dysgenesis has extreme variability, which may extend from a Turner-like syndrome to a male phenotype.

swyer syndrome

The etiology of 46 XY gonadal dysgenesis is though to be a short arm Y chromosome deletion involving SRY, a mutation in other genes that leads to inhibition of SRY function or mutation of SRY function. To date, 20% of 46 XY pure gonad dysgenesia are explained by a mutation or a deletion in SRY. In 80%, SRY is apparently normal. A female patient with an XY Karyotype who has a Palpable mullerian system, normal female testosterone levels, and lack of sexual development has Swyer syndrome, Tumor transformation in the gonadal ridge can occur at any age.


    Complete or pure gonadal dysgenesis. The patients are phenotypic females with a 46 XY karyotype and hypoplastic gonads without germ cells. They present most often with primary amenorrhea with normal stature. The gonads are usually streaks, but there may be some development of secondary sexual characteristics as well as a few episodes of uterine bleeding.

  • Mixed gonadal dysgenesis that primary amenorrhea is associated with various mosaic status, the most common of which is 45X/46xx. When compared to the pure 45X cell line, individuals with 45X/46XX are taller and have fewer abnormalities. Spontaneous menstruation occurs in approximately 20% of these patients.

  • Partial gonadal dysgenesis. They have karyotype 46XX with part of one of the X chromosomes missing. The phenotype is variable depending on the amount and location of the missing genetic material. In 46 XY partial gonadal dysgenesis individuals there is some testicular development; therefore they present as newborns with ambiguous genitalia.


The patients with Swyer syndrome patients arediagnosed in early adolescence with delayed pubertaldevelopment. As expected they show elevated gonadotropins (hormone secreted by the anterior pituitary gland and placenta; stimulates the gonads and controls reproductive activity), normal female levels of androgens and low levels ofestrogens, female external genitalia, uterus and fallopiantubes. Minimal breast enlargement reflects peripheral aromatization of androgens. Menstrual function suggeststumor development in the streak gonad. These streaksoften display ovarian stroma but no follicles.

Other Signs:

    Male pseudohermaphroditism.

  • Late puberty/hypogonadism

  • Abnormal ovaries.

  • Small/atrophic testes.

  • X-linked recessive inheritance.


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.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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