Research studies and findings which proposed a possible connection between premenstrual syndrome, prolactin levels, prostaglandins and γ-linolenic acid, an essential fatty acid precursor of prostaglandin E1, originate from the early 1980s [63,64], including first clinical studies showing success in the treatment with Oenothera oil, for premenstrual syndrome [65] and mastalgia [66]. The gene discussed is PRL; the disease is premenstrual tension.