Complete androgen insensitivity syndrome caused by a novel splice donor site mutation and activation of a cryptic splice donor site in the androgen receptor gene

• Androgen insensitivity syndrome is caused by mutations of the androgen receptor gene.
• We report a female with an XY karyotype and androgen-producing testis.
• We identified a novel AR splice donor site mutation in intron 4 (c.2173 + 2T > C).
• This mutation resulted in the activation of a cryptic splice donor site in exon 4.
• This rare splicing abnormality offers insight into the mechanisms of splicing defects.

The androgen insensitivity syndrome is an X-linked recessive genetic disorder characterized by resistance to the actions of androgens in an individual with a male karyotype. We evaluated a 34-year-old female with primary amenorrhea and a 46,XY karyotype, with normal secondary sex characteristics, absence of uterus and ovaries, intra-abdominal testis, and elevated testosterone levels. Sequence analysis of the androgen receptor (AR) gene revealed a novel splice donor site mutation in intron 4 (c.2173 + 2T > C). RT-PCR analysis showed that this mutation resulted in the activation of a cryptic splice donor site located in the second half of exon 4 and in the synthesis of a shorter mRNA transcript and an in-frame deletion of 41 amino acids. This novel mutation associated with a rare mechanism of abnormal splicing further expands the spectrum of mutations associated with the androgen insensitivity syndrome and may contribute to the understanding of the molecular mechanisms involved in splicing defects.