Abstract
Subjects with 47XYY often have normal amounts of gonadotropin-releasing hormone. In these subjects the association between 47XYY and 5-alpha reductase deficiency is rare. The common clinical manifestation of 5-alpha reductase deficiency is male pseudohermaphrodism, rarely it has been revealed by micropenis. Testosterone enanthate does not give good results in patients with 5-alpha reductase deficiency; dihydrotestosterone (DHT) has proven effectiveness in these cases. We report the case of a 17-year old patient, referred to our Hospital with micropenis. The patient didn't respond to two enanthate testosterone therapies. Assessment showed normal testosterone levels, amounts of gonadotropin-releasing hormone at the upper limit of normal, low DHT, elevated testosterone/DHT ratio>20, karyotype 47 XYY. This study highlights that 5-alpha reductase deficiency in these subjects raises the issue of simple coincidence or effective link.