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- Androgen
- pseudohermaphroditism
- sex chromosome
- X chromosome
androgen insensitivity syndrome
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What is androgen insensitivity syndrome?
Androgen insensitivity syndrome (AIS) is a rare, X-linked genetic disorder where individuals with XY chromosomes don't respond to male hormones called androgens. This resistance to androgens results in the feminization of male external genitalia to varying degrees.
Deletion of the receptor gene causes complete AIS (CAIS), where the external genitalia appear female. Reduced androgen receptor functionality results in partial AIS (PAIS), graded by the extent of feminization. AIS individuals are usually infertile but otherwise healthy. Treatment involves psychological support and hormone therapy. Diagnosis includes confirming the presence of a Y chromosome, male hormone levels, and the absence of a uterus.
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How does androgen insensitivity syndrome affect the body?
Androgen insensitivity syndrome (AIS) is a rare, X-linked genetic condition where a genetically male individual doesn't respond to male hormones (androgens). This resistance to androgens results in incomplete virilization (masculinization) of the external genitalia.
The severity of feminization varies depending on the androgen receptor's functionality. Complete AIS (CAIS) occurs when the receptor gene is deleted, resulting in female external genitalia. Reduced receptor function leads to partial AIS (PAIS), with varying degrees of feminization that may appear ambiguous at birth. Affected individuals are typically infertile but otherwise healthy. Treatment involves psychological support and hormone therapy, and the testes are usually surgically removed to prevent cancer.
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What causes androgen insensitivity syndrome?
Androgen insensitivity syndrome (AIS) is a rare X-chromosome-linked recessive genetic disorder that occurs when a genetically male individual cannot respond to male hormones called androgens. The degree of external feminization depends on the functionality of the androgen receptor. Complete AIS (CAIS) occurs when deletion of the receptor gene results in female external genitalia, while reduced androgen receptor functionality results in partial AIS (PAIS). Most individuals with AIS are infertile but otherwise healthy. Treatment includes psychological support and hormone therapy.
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How is androgen insensitivity syndrome inherited?
Androgen insensitivity syndrome (AIS) is a rare, X-chromosome-linked recessive genetic disorder where a genetically male individual cannot respond to male hormones called androgens. This disorder is caused by an inherited mutation on a single X chromosome. For a male offspring to inherit AIS, only one parent needs to pass on a copy of the defective gene on an X chromosome.
The degree of external feminization depends on the functionality of the androgen receptor. Complete AIS (CAIS) occurs when the receptor gene is deleted, resulting in female external genitalia. Reduced androgen receptor functionality results in partial AIS (PAIS), which is graded based on the extent of feminization.
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What are the different types of androgen insensitivity syndrome?
Androgen insensitivity syndrome (AIS) is a rare, X-chromosome-linked recessive genetic disorder where a genetically male individual is unable to respond naturally to androgens male hormones. The degree of feminization depends on the functionality of the androgen receptor.
Types of AIS:
* Complete AIS (CAIS) Deletion of the receptor gene results in complete AIS, in which the individual’s external genitalia appear female.
* Partial AIS (PAIS) Reduction in androgen receptor functionality results in partial AIS. PAIS is graded on the extent of feminization of external genitalia, which can be ambiguous at birth.Most individuals with AIS are infertile but are otherwise healthy. Treatment includes extended psychological support and hormone therapy.
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How is androgen insensitivity syndrome diagnosed and managed?
Androgen insensitivity syndrome (AIS) is a rare genetic disorder where individuals with a Y chromosome are resistant to androgen hormones. Diagnosis involves confirming the presence of a Y chromosome, testosterone levels typical of males, and imaging to check for intra-abdominal testes or the absence of a uterus.
Management includes psychological support for affected individuals and their families. Hormone therapy, appropriate for the individual's gender identity, usually starts at puberty. To prevent potential intra-abdominal testicular cancer, testes are surgically removed. Additional cosmetic treatments can include vaginal lengthening, vaginal construction, clitoral reduction, or breast reduction.
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androgen insensitivity syndrome (AIS), rare genetic disorder in which a genetically male individual fails to respond naturally to the effects of male hormones (also known as androgens). Androgen insensitivity syndrome (AIS) is an X-chromosome-linked recessive disorder, being caused by a mutation that is inherited on a single X chromosome. Inherited androgen resistance results in diminished virilization of the male external genitalia.
The degree to which the male external genitalia are feminized depends on the functionality of the androgen receptor. Deletion of the receptor gene results in complete AIS (CAIS), in which the individual’s external genitalia appear female. Reduction in androgen receptor functionality results in partial AIS (PAIS). PAIS is graded on the extent of feminization of external genitalia, which can be ambiguous at birth. Most individuals with AIS are infertile but are otherwise healthy. Treatment includes extended psychological support and hormone therapy.
Pathophysiology
Between the 8th and 10th week of gestation, male gonads begin producing testosterone, dihydrotestosterone, and Müllerian inhibiting factor, which are hormones critical to male development. In AIS, normal amounts of the hormones are produced, but properly functioning androgen receptors for testosterone and dihydrotestosterone are absent. In addition, exposure to Müllerian inhibiting factor causes internal male development, while unopposed testicular estrogen results in the development of external female genitalia.
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Presentation
Individuals with AIS lack internal female reproductive organs and do not menstruate, though the conversion of testosterone to estradiol enhances breast development. Only individuals with the mildest forms of PAIS are fertile. Most individuals have sparse armpit and pubic hair.
In CAIS, individuals have labia, a clitoris, and, at most, the distal two thirds of the vagina, though sometimes only a dimple is present. Because individuals with CAIS look female, they are rarely diagnosed in childhood unless a mass in the lower abdomen or groin is felt and imaging or surgery reveals an undescended testis. More often, CAIS individuals present to a physician during puberty when they fail to menstruate.
In PAIS, there may be undescended testes, a small penis, placement of the urethal opening on the underside of the penis, an enlarged clitoris, or fused labia. Owing to ambiguity, PAIS is often diagnosed in childhood. Otherwise, individuals will present to a clinician during puberty. If male identified, individuals often are concerned about breast development, whereas female-identified patients often are concerned about the lack of menstruation.
Diagnosis and treatment
Diagnosis is confirmed by the presence of a Y chromosome, male levels of testosterone and dihydrotestosterone, and, on imaging, intra-abdominal testes or an absent uterus. In addition to long-term counseling for individuals and families, support groups play a significant role in treatment. Gender-appropriate hormone therapy is usually started at puberty. Eventually, testes are surgically removed to prevent intra-abdominal testicular cancer that could be missed on physical examination.
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Optional cosmetic treatments include nonsurgical lengthening of the vagina, vaginal construction, or clitoral reduction. Breast reduction and repositioning of the urethral opening are surgical options in male-identifying AIS patients.