Complete Androgen Insensitivity Syndrome due to Mutations in the DNA-Binding Domain of the Human Androgen Receptor Gene.

Androgen insensitivity syndrome (AIS) is an X-linked recessive disorder with a 46,XY karyotype caused by alterations in the androgen receptor (AR) gene. We have identified 2 mutations in the AR gene that resulted in complete androgen insensitivity syndrome (CAIS) in 2 unrelated cases. This study includes cytogenetics, hormonal, molecular, and bioinformatics analysis including sequencing of the SRY (sex-determining region Y) and AR genes. Mutational analysis in the first case of primary amenorrhea revealed a novel nucleotide substitution (IVS2-2A>G) in the second intron of the AR gene. The mutation is located in the acceptor splice site (2 nucleotides before exon 3) and caused skipping of exon 3 and formation of an abnormal protein. The second mutation (g. 98762_98764delTCT) was identified in a case of oligoamenorrhea and caused the deletion of 1 amino acid (p.∆Phe583). Both identified mutations were located in the conserved P-box region of the DNA-binding domain which is responsible for base-specific contacts with the DNA major groove. Furthermore, a hormonal imbalance was also noticed in both cases with high levels of gonadotropins like FSH and LH in both cases. The present study concluded that both identified AR mutations are predicted to either abolish or decrease the binding ability of the AR to androgen response elements of its downstream genes.