A single amino acid substitution (gly743 --> val) in the steroid-binding domain of the human androgen receptor leads to Reifenstein syndrome

Abstract

The androgen receptor (AR) from a patient with Reifenstein syndrome (incomplete androgen insensitivity syndrome) was characterized. The patient's pubic skin fibroblasts had normal androgen binding. However, when incubated at 41 C, fibroblasts from the patient had a marked decrease in androgen binding as compared with normal fibroblasts. Analysis of coding sequences of the androgen receptor gene revealed a single nucleotide substitution in exon E, resulting in an amino acid change from glycine (GGG) to valine (GTG) at amino acid 743 within the steroid binding domain of AR. Reconstruction of this mutation by site-directed mutagenesis into a human AR complementary DNA followed by expression in COS1 cells led to production of a mutant AR with no significant difference in androgen binding when cells were incubated with androgen at room temperature. However, in contrast to wild type AR expressed in COS1 cells, the mutant AR had markedly lower androgen-binding affinity at 41 C. The mutant receptor could still stimulate a reporter gene at 37 C but this transcriptional stimulation was also decreased when compared with wild type AR receptor in a chloramphenicol acetyltransferase assay. These results suggest that partial androgen resistance in this patient with Reifenstein syndrome is due to a single point mutation in the steroid binding domain of the androgen receptor.