Molecular basis of androgen insensitivity

Mutations in the androgen receptor gene in 46,XY individuals can be associated with the androgen insensitivity syndrome, of which the phenotype can vary from a female phenotype to an undervirilized or infertile male phenotype. We have studied the androgen receptor gene of androgen insensitivity patients to get information about amino acid residues or regions involved in DNA binding and transcription activation. Genomic DNA was analysed by PCR-SSCP under two different conditions. Three new mutations were found in exon 1 of three patients with a female phenotype. A cytosine insertion at codon 42 resulted in a frameshift and consequently in the introduction of a premature stop at codon 171. Deletion of an adenine at codon 263 gave rise to a premature stop at codon 292. In both these cases, receptor protein was not detectable and hormone binding was not measurable. In a third patient, a guanine-to-adenine transition at codon 493 converted a tryptophan codon into a stop codon. Genital skin fibroblasts from this patient were not available. In exon 2 of the androgen receptor gene of a patient with receptor-positive androgen insensitivity, a cytosine-to-adenine transition, converting alanine 564 into an aspartic acid residue, resulted in defective DNA binding and transactivation. In three other receptor-positive androgen insensitivity patients no mutations were found with PCR-SSCP.