A New Missense Substitution at a Mutational Hot Spot of the Androgen Receptor in SiblingsWith Complete Androgen Insensitivity Syndrome

Several mutations have been described in the human androgen receptor gene including constitutional mutations in androgen insensitivity syndrome, somatic mutations in prostate cancer and triplet expansions in Kennedy's disease (Gottlieb et al. 1997). Here we report on two siblings with complete androgen insensitivity and a novel missense mutation, D695V, in their androgen receptor gene. The two XY females are siblings of German descent and presented at the ages of 23 and 19 years, respectively, with typical clinical features of complete androgen insensitivity. We found both siblings to be hemizygous for a new adenine to thymine transversion at the second nucleotide of codon 695 within the fourth exon of the human androgen receptor gene. The resulting missense mutation D695V is located at the amino‐terminal border of the ligand‐ binding domain of the androgen receptor. The aspartic acid residue at this position is highly conserved in the steroid binding domains of other members of the nuclear receptor family and has already been found to be the site of two other missense mutations associated with androgen insensitivity syndrome (Ris Stalpers et al. 1991, Hiort et al. 1996). Three of four reported subjects showed the complete androgen insensitivity phenotype, in accordance with the two siblings in our study. We suggest that the existence of three pathological amino acid substitutions for aspartic acid 695 most likely reflects the essential role of this residue for normal androgen receptor function in male sexual differentiation.