Interestingly, androgenreceptor-deficient zebrafish males are strikingly similar phenotypically to thevipa−/− male (eg, smaller testis size, infertility when testedby natural mating, and only a small amount of mature spermatozoa with a lower fertilizationcapacity by in vitro fertilization) (67).This suggests that loss of function of a single androgen synthesis gene results in amoderate response compared to the more dramatic disruption caused by the inactivation of theandrogen receptor. The gene discussed is AR; the disease is Infertility.