A novel insA2933 causes premature termination of translation and is accompanied by overexpression of truncated androgen receptor gene in a patient with complete androgen insensitivity syndrome

A patient with a female phenotype, 46,XY karyotype, and a diagnosis of complete androgen insensitivity syndrome (CAIS) was examined. Her mother and three 46,XX sisters were also included in the study. Sequence analysis of the androgen receptor gene (AR) revealed a novel A2933 insertion that alters the Tyr codon to a termination codon (Y857X), resulting in a truncated form of the receptor. Computer simulation revealed major conformational changes in the hydrophobic pocket that accommodates the hormone. An insA2933 results in a truncated receptor incapable of binding the ligand and is responsible for the clinical symptoms of CAIS in the patient. The levels of the AR transcript in peripheral blood leukocytes were higher in the patient than in her heterozygous mother and her heterozygous sister, as well as in the two healthy sisters. It is hypothesized that elevated levels of the AR transcript in the patient might be caused by the inability of the truncated receptor to react with IFI-16, which functions in complex with AR to inhibit the expression of the AR gene.