Impaired spermatogenesis is not an obligate expression of receptor‐defective androgen resistance

Abstract

We are studying a man who presented at age 21 years with severe extragenital subvirilization despite high‐normal to above‐normal levels of plasma testosterone for at least 5 years. At puberty, his penis, scrotum, and testes matured normally, and he did not develop gynecomastia; however, his voice, muscularity, and facial, sexual, and body hair remained immature. A 2.5‐ml ejaculate yielded normal results for sperm density, morphology, and motility. Because persistent undervirilization was emotionally disabling, he has received pharmacologic doses of testosterone enanthate intramuscularly for 3.5 years. The treatment has improved his virilization and masculine self‐image substantially, and his semen analysis has remained well within the normal range. The androgen receptor in his genital skin fibroblasts has a distinctively mutant phenotype: it has a low affinity (increased apparent equilibrium dissociation constant, K_d) for 5α‐dihydrotestosterone and two synthetic androgens, mibolerone (MB) and methyltrienolone (MT), and its binding capacity (B_max) is normal for the other two ligands, but questionably low for MT. In addition, it up‐regulates its activity normally in response to prolonged incubation with androgen, and its androgen‐receptor complexes are not thermolabile. Our study of this man permits two conclusions: impaired spermatogenesis is not the irreducible expression of receptor‐defective androgen resistance in man; and androgen pharmacotherapy may be remedial for those in whom extragenital subvirilization is emotionally costly and subnormal spermatogenesis is not an inevitable side effect of such therapy.