PGR and biliary tract disorder: Estrogen receptors (ESR1, ESR2) and progesterone receptor (PGR) genes are located on chromosome 6q25.1, 14q21–22 and 11q22 respectively and their expression have been detected in human gallbladder normal mucosa [15] and GBC [16] Allelic variants of estrogen receptor genes have been shown to be associated with susceptibility or progression with various disorders such as myocardial infarction [17], cholesterol gallstone and biliary tract diseases [18].