GASTROENTEROLOGY Cholecystokinin receptor A gene polymorphism in gallstone disease and gallbladder cancer Anvesha Srivastava,* Sachchida Nand Pandey,* Manjusha Dixit,* Gourdas Choudhuri † and Balraj Mittal* Departments of *Genetics and † Gastroenterology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India Abstract Background and Aim: Gallbladder carcinoma (GBC) usually arises in the background of gallstone disease which may be causatively related to decreased gallbladder contractility. Cholecystokinin receptor A (CCK-AR) mediates signals resulting in gallbladder contrac- tion. Deteriorating gallbladder contraction promotes gallstone formation. A common genetic polymorphism of CCK-AR may be causatively associated with the risk of gallstone and GBC. This study aimed to understand the association of CCK-AR Pst I polymorphism in gallstone disease with gallbladder cancer. Method: This study included 165 gallstone patients, 139 GBC patients, and 190 healthy subjects. Genotyping was done using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) method. Results: The frequency of the A1A1 genotype of CCK-AR was significantly higher in gallstone patients than healthy individuals (P = 0.008 odds ratio [OR] = 2.25, and 95% confidence interval [CI]:1.2–4.1). However, there was a significant difference in the fre- quency of A1A1 genotype when gallstone patients were compared to GBC patients (P = 0.041, OR = 0.49, and 95% CI: 0.3–0.9). On stratification of GBC patients according to presence or absence of gallstones, GBC patients without stones were compared to controls and GBC patients with stones were compared to stone patients; however, no significant differences in frequencies were observed. Conclusion: The results suggest that the A1A1 genotype of CCK-AR is an independent genetic risk factor for gallstone disease and does not modulate the susceptibility of gall- bladder cancer. Key words cholecystokinin receptor, gallbladder cancer, gallstone, polymorphism, PCR-RFLP. Accepted for publication 24 July 2007. Correspondence Dr Balraj Mittal, Department of Genetics, SGPGIMS, Lucknow-226014 (UP), India. Email: balraj@sgpgi.ac.in Introduction Gallstone is a multifactorial disease affecting 5–10% of the adult population in which both genetic and environmental factors con- tribute towards susceptibility. The prevalence of gallstones in north India has been found to be around at least 6% of the adult popu- lation. 1,2 Gallstones are causatively related to cholesterol hyperse- cretion and gallbladder hypomotility. However, long-standing gallstones have been attributed to the pathogenesis of gallbladder carcinoma. 3,4 Gallbladder carcinoma (GBC) is a grave disease with poor prognosis. It is the most common malignant lesion of the biliary tract, the fifth-most common malignant neoplasm of the digestive tract and also the most common gastrointestinal cancer in women. 5–7 The etiology of GBC is complex and associated risk factors identified so far include cholelithiosis, obesity, reproduc- tive factors, chronic infection, environmental exposure to specific chemicals, and genetic factors. 8–14 Gallstone disease and gallbladder carcinoma affects two to six times more women than men and worldwide the geographic vari- ability of GBC incidence usually parallels with the prevalence of cholelithiasis. 5,6,13,15 Fifty to 85% of patients with GBC have cholelithiasis and the risk of GBC increases in direct proportion to gallstone size. 13,15 In animal models, gallbladder inflammation is an early feature of gallstone formation. 16 In a large human study, cholelithiasis and cholecystitis have been found to produce a series of pathologic changes such as simple epithelial hyperplasia, atypi- cal hyperplasia, and carcinoma in situ, which represent the pre- cancerous lesions of gallbladder carcinoma. 15,17,18 Supersaturation of bile with cholesterol has been primarily implicated in gallstone formation. Hypomotility of gallbladder due to impaired signaling leads to stasis of bile. Deteriorating gallblad- der contraction provides the time necessary for cholesterol nucle- ation and the retention of precipitated microcrystals which agglomerate into stones. Impaired gallbladder emptying has been reported in patients with cholesterol gallstones, resulting from the defect in the CCK-A receptor in the gallbladder. 19 Cholecystokinin (CCK) is a peptide hormone known to be a potent regulator of gastrointestinal motility and stimulates post- prandial gallbladder contractions. The biological actions of CCK in the alimentary canal are mediated by the CCK-A receptor (CCK-AR). 20,21 CCK-AR is a seven-transmembrane spanning doi:10.1111/j.1440-1746.2007.05170.x 970 Journal of Gastroenterology and Hepatology 23 (2008) 970–975 © 2007 The Authors Journal compilation © 2007 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd