Estrogen receptors α and β have been found on cholangiocytes of cystic tissue from polycystic liver disease patients, while these receptors are absent in normal biliary structures of either polycystic liver disease patients or healthy controls.[6] Addition of estradiol increases the proliferation of liver cyst-derived cholangiocytes in vitro.[6] If estrogen receptor degraders such as fulvestrant are added, proliferation is significantly slowed.[6] A possible role of progesterone in PLD remains to be elucidated. The gene discussed is ESR1; the disease is Isolated polycystic liver disease.