Androgen gene mutation in hypospadias: a genetic and functional analysis

Objective; Hypospadias has no known single etiology. Defects in the androgen receptor (AR) gene may result in partial or incomplete androgen insensitivity syndrome producing a spectrum of phenotypes including hypospsadias. We screened for AR gene mutations in various grades of hypospadias, determined associations with anatomic or pedigree subgroups, and evaluated the functional changes of the AR in individuals with a mutation. Materials: Genomic DNA was extracted from tissue samples of 45 patients undergoing reconstructive surgery. When needed, DNA from blood samples of family members was also evaluated. Exons 2-8 of the AR gene were amplified individually by polymerase chain reaction. Single-strand conformational polymorphism (SSCP) analysis was then performed by electrophoresis in a nondenaturing acrylamide gel. In cases with variant band shifts on the SSCP, sequence analysis of the DNA was performed to define the mutation. Functional consequences of a mutation were analyzed by transient transfection of mutant and wild-type AR into PC-3 cells and 286 probasin-CAT constructs. Results: A missense mutation of exon 2 of the AR gene was noted in 1 patient with isolated distal hypospadias. Sequence analysis revealed a proline to serine change in amino acid residue 546. This mutation was also found in this patient's mother, a heterozygote, and four other family members consistent with an Xlinked hereditary pattern. No change in receptor activity was noted using a simple promoter reporter construct, but lower activity of the mutant receptor was seen using the complex promoter, 286 PB-CAT. No abnormalities were detected in the other 44 patients, and specifically none in 5 additional patients with a definite maternal family history for hypospadias. Conclusions! In rare cases, isolated distal shaft hypospadias can be associated with an androgen receptor gene mutation with associated hormonal functional changes.

Duke Scholars

Author John Samuel Wiener Urology