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Androgen insensitivity syndrome is a condition that affects sexual development before birth and during puberty. People with this condition are genetically male, with one X and one Y chromosome. Because their bodies are unable to respond to certain hormones (called androgens), they may have mostly female sexual characteristics or signs of both male and female sexual development (hermaphroditism).
Complete androgen insensitivity syndrome occurs when the body cannot use androgens at all. Partial or mild androgen insensitivity syndrome results when tissues are partially sensitive to the effects of androgens. People with partial androgen insensitivity (also called Reifenstein syndrome) can have normal female sexual characteristics, both male and female sexual characteristics, or normal male sexual characteristics. People with mild androgen insensitivity appear male, but are often infertile and tend to develop female breasts at puberty.
Complete androgen insensitivity syndrome affects 2 to 5 per 100,000 live male births. Partial androgen insensitivity is at least as common as complete androgen insensitivity. Mild androgen insensitivity is much less common.
Mutations in the AR gene cause androgen insensitivity syndrome.
The AR gene provides instructions to make a protein called an androgen receptor. This protein allows cells to respond to androgens, which are hormones (such as testosterone) that direct male sexual development. Androgens and androgen receptors also have other important functions in both males and females, such as regulating hair growth and sex drive. Mutations in the AR gene prevent the androgen receptor from working properly, which makes cells less responsive to androgens or prevents cells from using these hormones at all. Depending on the level of androgen insensitivity, an affected person's sexual characteristics can vary from mostly female to mostly male.
This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome) one altered copy of the gene in each cell is sufficient to cause the condition. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
About two-thirds of cases are inherited from mothers who carry an altered copy of the AR gene on one of their two X chromosomes. The remaining cases result from a new mutation in a mother's egg cell before the child is conceived.
'''Androgen insensitivity syndrome''' ('''AIS''') is a set of disorders of sexual differentiation that results from mutations of the gene encoding the androgen receptor. It has also been called ''androgen resistance'' in the medical literature. The nature of the resulting problem varies according to the structure and sensitivity of the abnormal receptor. Most of the forms of AIS involve variable degrees of undervirilization and/or infertility in XY persons of either sex. A woman with complete androgen insensitivity syndrome (CAIS) has a nearly normal female body despite a 46XY karyotype and testis, a condition termed ''testicular feminization'' in the past. Major changes in the understanding and management of the various forms of AIS have occurred since 1990. Laboratory research has greatly expanded our understanding of the molecular mechanisms of the clinical features, including a rare neuromuscular disorder. More importantly, patient advocacy groups for AIS and other intersex conditions have increased public awareness of these disorders, helped revise our understanding of gender identity, emphasized the value of accurate and sophisticated information for patients, and induced physicians to re-evaluate the effectiveness of the intersex surgery attempted in past decades. Surgery is increasingly seen as a very elective option even for the more ambiguous genitalia conditions.
AIS Nederland - Staat voor: Androgen Insensitivity Syndrome, een aangeboren aandoening van het voortplantingssysteem.
Hypospadias - Why it happens, what it is, what to do; see photos of hypospadias and contact others with it. Discusses androgen insensitivity, testicular feminization syndrome, development, and even ISNA.
AIS (Androgen Insensitivity Syndrome) Support Group - This site contains medical information about Androgen Insensitivity, support group contacts, newsletters and personal accounts of people with AIS
Androgen Insensitivity Syndrome (AIS) - Offers medical information from the National Institute of Health.
AIS (Androgen Insensitivity Syndrome) Support Group - Worldwide. Includes medical information about Androgen Insensitivity, support group contacts, newsletters and personal accounts of people with AIS