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Androgen insensitivity syndrome is a type of genetic disorder. It occurs when a person has the genes of a male but his body is resistant to androgens, which are male hormones. This resistance to male hormones causes the affected person to have many or all of the outward characteristics of a female. Usually, this disorder is caused by a defect of one of the chromosomes that determines sex: the X chromosome. Such a defect interferes with the hormones that would normally give a person male physical characteristics.
Sex chromosomes, called X and Y chromosomes, are responsible for determining whether a person will be male of female. When a person has two X chromosomes, she is considered a female; one Y and one X chromosome, however, indicates that the individual is male. Genetic gender does not change when a person has androgen insensitivity syndrome, and having one Y and one X chromosome still means that the person is male. The X chromosome, however, is affected in such a case and cannot respond fully or at all to androgens. As such, a person may have some characteristics of both a male and a female or appear to be entirely female.
There are two types of androgen insensitivity syndrome: complete androgen insensitivity syndrome and partial androgen insensitivity syndrome. With complete androgen insensitivity, the affected person is entirely resistant to androgens. In such a case, he usually appears to be entirely female, which includes the appearance of his genitals. Genetically, however, the patient is male and will lack a uterus and ovaries. Often, children who are born with complete androgen insensitivity are raised as if they were female.
Partial androgen insensitivity syndrome is marked by a low level of sensitivity to androgens. The physical characteristics of a person with partial androgen sensitivity depend on the degree to which the affected person is sensitive to androgens. Some people with this condition will appear outwardly male while others may appear to be female. In some cases, a person with this disorder may even have both female and male physical characteristics.
There is no cure for androgen insensitivity syndrome. Doctors may, however, prescribe estrogen replacement therapy in order to prevent the symptoms of menopause in a patient who is outwardly female. Genital reconstruction therapy may also help in some cases. Often, surgery is used to remove testicles that have failed to descend. Additional, psychological counseling may benefit patients who have androgen insensitivity syndrome.