In case of breast adenocarcinoma, it was shown that Kv1.3 gene promoter was methylated only in 12.5% (2/16) of patients with the Grade I of the disease (SBR Histological Grade), but in 52.2% (12/23) and in 53.9% (7/13) of patients with the Grade II and III, respectively (24). The gene discussed is KCNA3; the disease is breast adenocarcinoma.