title: Parathyroid hormone gene rs6256 and calcium sensing receptor gene rs1801725 variants are not associated with susceptibility to colorectal cancer in Iran.
abstract: BACKGROUND
  Substantial evidence from epidemiological studies has suggested that increased levels of calcium may play a protective role against colorectal cancer (CRC). Given the vital role of calcium sensing receptor (CaSR) and parathyroid hormone (PTH) in the maintenance of calcium homeostasis, we explored whether the rs1801725 (A986S) variant located in exon 7 of the CaSR gene and the rs6256 variant located in exon 3 of PTH gene might be associated with CRC risk.
  
  
  METHODS
  In this study 860 subjects including 350 cases with CRC and 510 controls were enrolled and genotyped using PCR-RFLP methods.
  
  
  RESULTS
  We observed no significant difference in genotype or allele frequencies between the cases with CRC and controls for both CaSR and PTH genes either before or after adjustment for confounding factors including age, BMI, sex, smoking status, and family history of CRC. Furthermore, no evidence for effect modification of any association of rs1801725 and rs6256 variants and CRC by BMI, sex, or tumor site was observed. In addition, there was no significant difference in genotype and allele frequencies between the normal weight (BMI<25 kg/m2) cases and overweight/ obese (BMI≥25 kg/m2) cases for the two SNPs.
  
  
  CONCLUSIONS
  These data indicated that the CaSR gene A986S variant is not a genetic contributor to CRC risk in the Iranian population. Furthermore, our results suggest for the first time that PTH gene variant does not affect CRC risk. Nonetheless, further studies with larger sample size are needed to validate these findings.
authors.affiliation: Gastroenterology and Liver Diseases Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran E-mail : mahmouditouraj@gmail.com.
authors.forename: Touraj
authors.initials: T
authors.lastname: Mahmoudi
authors.forename: Khatoon
authors.initials: K
authors.lastname: Karimi
authors.forename: Maral
authors.initials: M
authors.lastname: Arkani
authors.forename: Hamid
authors.initials: H
authors.lastname: Farahani
authors.forename: Hossein
authors.initials: H
authors.lastname: Nobakht
authors.forename: Reza
authors.initials: R
authors.lastname: Dabiri
authors.forename: Asadollah
authors.initials: A
authors.lastname: Asadi
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003106:Colon / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004247:DNA / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D007492:Iran; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010281:Parathyroid Hormone / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D011379:Prognosis; D044169:Receptors, Calcium-Sensing / Q000235:genetics*; D012007:Rectum / Q000378:metabolism; D055815:Young Adult
chemical_list: C095550:CASR protein, human; C470125:PTH protein, human; D010281:Parathyroid Hormone; D044169:Receptors, Calcium-Sensing; D004247:DNA