Background: Androgen insensitivity syndrome is an X-linked disorder of male sexual differentiation caused by mutations in the androgen receptor gene and resulting in a wide range of phenotypes.
Objective: To study the androgen receptor gene in two cousins with androgen insensitivity syndrome.
Patients and methods: We present two patients who attended our clinic for primary amenorrhea. The phenotype and external genitalia were female. Pelvic ultrasonography showed the absence of uterus and female internal genitalia. In both patients the karyotype was 46 XY and consequently both patients underwent bilateral gonadectomy. Histological examination confirmed that the gonads were testes. Molecular study of the androgen receptor gene was performed to confirm androgen insensitivity syndrome.
Results: Both patients showed a thymine deletion in exon 5 at nucleotide 2298 (codon CCT for proline 766) of the androgen receptor gene, causing their phenotype.
Conclusions: To confirm androgen insensitivity syndrome,t he androgen receptor gene should be analyzed for mutations, although the relationship between genotype and phenotype is weak. To detect carriers of the mutation, karyotyping and study of the androgen receptor gene should be performed in girls who are first relative of the probands.