While prolactin overproduction could lead to galactorrhea and has an inhibitory effect on the release of gonadotropin-releasing hormone that results in functional infertility, menstrual cycle disturbances in young women and decreased libido and spermatogenesis in men, the hypo-prolactinemic situation does not show any striking clinical picture apart of the impossibility to lactate during the puerperium. This evidence concerns the gene PRL and Galactorrhea.