Molecular basis of androgen insensitivity

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• Male sexual development is regulated by androgens and mediated by the androgen receptor (AR).
• Androgen insensitivity syndrome (AIS) arises from defects in the AR gene, impacting sexual differentiation in 46,XY individuals.
• Disorders of androgen action result from partial AR impairment, leading to varied sexual development phenotypes.

Purpose of the Study:

• To review the genetic basis and clinical manifestations of androgen insensitivity syndrome.
• To explore the spectrum of disorders related to androgen receptor dysfunction.
• To discuss the molecular etiology of Kennedy's disease as an AR-related disorder.

Main Methods:

• Literature review of studies on androgen receptor gene mutations and associated clinical conditions.
• Analysis of genotype-phenotype correlations in patients with complete and partial AIS.
• Examination of the molecular mechanisms underlying Kennedy's disease.

Main Results:

• Complete AIS is characterized by a female phenotype in 46,XY individuals, often due to mutations in AR exons 2-8.
• Partial AIS presents with ambiguous genitalia or predominantly male/female phenotypes, linked to mutations in AR exons 5 and 7.
• Kennedy's disease, an X-linked motor neuron disease, is caused by expanded polyglutamine tracts in the AR N-terminal domain.

Conclusions:

• Androgen receptor gene mutations are the primary cause of androgen insensitivity syndromes, with specific mutation sites correlating to disease severity.
• Understanding AR gene defects is crucial for diagnosing and managing disorders of sexual development and related neurological conditions.
• The AR gene plays a critical role in both sexual development and neuronal function, as evidenced by AIS and Kennedy's disease.