title: p21 Waf1/Cip1 polymorphisms and risk of esophageal cancer.
abstract: BACKGROUND
  As the main downstream effecter of tumor suppressor p53, p21(Waf1/Cip1) functions as a unique link from p53 to cell-cycle arrest and DNA repair. In contrast to p53, p21(Waf1/Cip1) has general rare mutations. The natural genetic variants of p21(Waf1/Cip1) have thus emerged for study to enhance understanding of interindividual differences in cancer risk. Two polymorphisms in the p21 ( Waf1/Cip1 ) gene, i.e., codon 31 in the coding region and IVS2+16 in intron 2, have been identified and appeared to influence the expression of p21(Waf1/Cip1). The aim of this study is to investigate the potential association of the above two variants, including one new single-nucleotide polymorphism (SNP) 309 in the promoter region of p21 ( Waf1/Cip1 ), with susceptibility to esophageal cancer (EC).
  
  
  METHODS
  The study involved 80 cancer patients and 200 cancer-free controls from Ningxia Region of China. Three variations (codon 31, IVS2+16, and SNP 309) were identified by polymerase chain reaction (PCR) direct sequencing method, and associations of each individual SNP and haplotypes of the three SNPs with esophageal cancer were analyzed.
  
  
  RESULTS
  The correlation results supported that codon 31 Ser homozygosity conferred risk for the process of developing EC [odds ratio (OR) = 2.542, 95% confidence interval (CI) = 1.347-4.730]. In the combined study of the three variations, HapA and HapB appeared to influence the risk of EC.
  
  
  CONCLUSIONS
  Our findings indicated that codon 31 Ser allele homozygosity, either alone or in combination with the other two SNPs, may be associated with development of EC. These findings warrant validation in a larger study of EC patients.
authors.affiliation: Department of Biotechnology, School of Basic Medical Science, Ningxia Medical University, Yinchuan, Ningxia, People's Republic of China. ywjmd@yahoo.com.cn
authors.forename: Wenjun
authors.initials: W
authors.lastname: Yang
authors.forename: Qi
authors.initials: Q
authors.lastname: Qi
authors.forename: Heng
authors.initials: H
authors.lastname: Zhang
authors.forename: Wenda
authors.initials: W
authors.lastname: Xu
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yin
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Dong
authors.forename: Haiyan
authors.initials: H
authors.lastname: Jiao
authors.forename: Zhenghao
authors.initials: Z
authors.lastname: Huo
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D016022:Case-Control Studies; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000473:pathology; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006239:Haplotypes / Q000235:genetics; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012307:Risk Factors; D015996:Survival Rate
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004273:DNA, Neoplasm