A single exchange of an alanine to a threonine at amino acid position 596 in the androgen receptor has been identified as an inheritable trait in patients with Reifenstein syndrome. This exchange is a result of a germ line mutation in the genomic DNA sequences that make up the D-loop of the receptor. The D-loop and sequences in the hormone binding domain together provide the interacting surfaces for receptor dimer formation and subsequent binding to DNA. Here we show that the single amino acid exchange abolishes dimerization of the receptor. With this finding we demonstrate that the destruction of dimerization of the androgen receptor is one of the causes of Reifenstein syndrome.