Therefore, in the presence of a normal gonadal function three possible mechanistic scenarios can be hypothesized (Figure 6): (i) MD adherence associates with a better profile of the hypothalamic-pituitary-gonadal axis (HPTA) and testicular function; (ii) MD adherence likely associates with a better testicular sensitivity to FSH, resulting in a correct spermatogenic function and semen profile; (iii) MD might influence sperm production and spermiogenesis by the association with a reduced negative feedback at the central level. The gene discussed is BRD2; the disease is Menkes disease.