Study on the Frequency of Receptor Insensitivity to Androgen Using the Androgen-receptor Binding Assay in the Genetic Male Children with Abnormalities of Sexual Differentiation

ABSTRACT

PURPOSE: The development of external genitalia in genetic male is dependent on the transcriptional regulatory activity of dihydrotestosterone(DHT)-androgen receptor complex in the genital skin. The abnormality of androgen receptor encompasses a wide range of phenotypes. We investigated the androgen receptor binding capacity of genetic males with ambiguous genitalia(grade was determined by Prader grade) for the availability as screening test. METHODS: The binding capacity of the androgen receptor was assessed in fibroblasts established from foreskin or pubic area skin of genetic male [normal control(n=5); Prader grade 2, 3(P23; n= 5); Prader grade 4, 5, 6(P456; n=4), Prader grade 7(P7; n=2)]. RESULTS: There was no significant difference in averages of Bmax(maximum binding capacity) and Kd(equilibrium dissociation constant) of [3H]DHT to the androgen receptor between those of controls and P23. In P456, Bmax was decreased in two patients and Kd was increased in one patient. Bmax and Kd were normal in one patient. In P7, specific binding was not documented and compatible with androgen insensitivity syndrome. CONCLUSION: In genetic male with complete female phenotype without pubic hair(P7), the binding study may be useful as a diagnostic tool. But in genetic male with hypospadia(P23) or incomplete female phenotype(P456), the binding study is not useful as a diagnostic test.