Novel molecular defects in the androgen receptor gene of Mexican patients with androgen insensitivity

The androgen insensitivity syndrome (AIS) is an X-linked form of male pseud ohermaphroditism caused by mutations in the androgen receptor (AR) gene. In the present study, we analyzed the AR gene in 8 patients, 4 sporadic and 2 familial cases with the syndrome, using exon-specific polymerase chain rea ction, single-stranded conformational polymorphism and sequencing analysis and identified six new single base mutations, including one nonsense mutati on at the hinge region of the receptor. These molecular lesions occurred in the steroid-binding domain (SBD) and all but one affected the first nucleo tide of their respective codons. A nonsense mutation in exon 4, which conve rts a glutamine into a premature termination signal (Q657stop), a missense mutation changing arginine instead of glycine (G743R) and a conservative su bstitution of leucine with valine at amino acid 830 (L830V) were detected i n patients with CAIS. Three other missense mutations located in exons 4 (L7 01I), 5 (A765S), and 6 (Q802R) were present in individuals bearing a partia l form of AIS. These data allow us to reaffirm the view that nonsense mutat ions in the AR results almost invariably in a CAIS phenotype and underly th e importance of the SBD for the AR functional activity.