Defects in AR are the cause of androgen insensitivity syndrome (AIS) [MIM:300068]; previously known as
testicular feminization syndrome (TFM). AIS is an X-linked recessive form of pseudohermaphroditism due
end-organ resistance to androgen. Affected males have female external genitalia, female breast development,
blind vagina, absent uterus and female adnexa, and abdominal or inguinal testes, despite a normal 46,XY karyotype.
Defects in AR are the cause of spinal and bulbar muscular atrophy X-linked type 1 (SMAX1) [MIM:313200];
also known as Kennedy disease. SMAX1 is an X-linked recessive form of spinal muscular atrophy. Spinal
muscular atrophy refers to a group of neuromuscular disorders characterized by degeneration of the anterior
horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy. SMAX1 occurs only in men.
Age at onset is usually in the third to fifth decade of life, but earlier involvement has been reported.
It is characterized by slowly progressive limb and bulbar muscle weakness with fasciculations, muscle
atrophy, and gynecomastia. The disorder is clinically similar to classic forms of autosomal spinal
muscular atrophy. Note=Caused by trinucleotide CAG repeat expansion. In SMAX1 patients the number of
Gln ranges from 38 to 62. Longer expansions result in earlier onset and more severe clinical manifestations of the disease.
Note=Defects in AR may play a role in metastatic prostate cancer. The mutated receptor stimulates
prostate growth and metastases development despite of androgen ablation. This treatment can reduce
primary and metastatic lesions probably by inducing apoptosis of tumor cells when they express the wild-type receptor.
Defects in AR are the cause of androgen insensitivity syndrome partial (PAIS) [MIM:312300]; also
known as Reifenstein syndrome. PAIS is characterized by hypospadias, hypogonadism, gynecomastia, genital
ambiguity, normal XY karyotype, and a pedigree pattern consistent with X-linked recessive inheritance.
Some patients present azoospermia or severe oligospermia without other clinical manifestations.
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