The frequency of the rs2734849*С allele of the ANKK1 gene in the total group was significantly higher in patients with HPRL compared to patients with normal level of prolactin (Table 2; χ2 = 3.7; p = 05; OR 1.30; 95%Cl: 0.99–1.69). The gene discussed is PRL; the disease is familial hyperprolactinemia.