Complete androgen insensitivity syndrome caused by a deep intronic pseudoexon-activating mutation in the androgen receptor gene.

Johanna Känsäkoski,Mikko J Frilander,Jarmo Jääskeläinen,Lilli Saarinen,Rainer Lehtonen,Johanna Tommiska,Tiina Jääskeläinen,Taneli Raivio,Jorma J Palvimo,Sampsa Hautaniemi,Jorma Toppari

doi:10.1038/srep32819

Abstract

Mutations in the X-linked androgen receptor (AR) gene underlie complete androgen insensitivity syndrome (CAIS), the most common cause of 46,XY sex reversal. Molecular genetic diagnosis of CAIS, however, remains uncertain in patients who show normal coding region of AR. Here, we describe a novel mechanism of AR disruption leading to CAIS in two 46,XY sisters. We analyzed whole-genome sequencing data of the patients for pathogenic variants outside the AR coding region. Patient fibroblasts from the genital area were used for AR cDNA analysis and protein quantification. Analysis of the cDNA revealed aberrant splicing of the mRNA caused by a deep intronic mutation (c.2450-118A>G) in the intron 6 of AR. The mutation creates a de novo 5′ splice site and a putative exonic splicing enhancer motif, which leads to the preferential formation of two aberrantly spliced mRNAs (predicted to include a premature stop codon). Patient fibroblasts contained no detectable AR protein. Our results show that patients with CAIS and normal AR coding region need to be examined for deep intronic mutations that can lead to pseudoexon activation.

Highlights

We demonstrate a new mechanism for CAIS
The normal-sized product of 683 bp was much fainter in the patient samples than in the controls (Fig. 1a). These findings suggested a splicing defect caused by a deep intronic mutation between exons 5 and 8
Several splicing mutations of AR have already been reported in Androgen insensitivity syndrome (AIS) patients, most are situated in the conserved splice sites close to the exon-intron junctions

Summary

Introduction

We show that a deep intronic pseudoexon-activating mutation in the intron between exons 6 and 7 of AR, detected in two siblings with CAIS with normal AR coding region and conserved splice sites, leads to aberrant splicing of the AR mRNA and insufficient AR protein production. The normal-sized product of 683 bp was much fainter in the patient samples than in the controls (Fig. 1a).

Results

Conclusion