title: [Association of genetic variantions of circadian clock genes and risk of breast cancer].
abstract: OBJECTIVE
  To investigate the relationship between genetic variantions of circadian clock genes and risk of breast cancer.
  
  
  METHODS
  A case-control study including 406 breast cancer patients and 412 controls was conducted and genes Clock (rs2070062) and Per2 (rs2304672, rs2304669, rs934945) were genotyped by TaqMan real-time PCR. Unconditional logistic regression model was used to analyze the association between the genetic polymorphisms and breast cancer.
  
  
  RESULTS
  Individuals with the rs2304669-TT genotype showed significantly increased breast cancer risk with the OR of 2.33 when compared with the individuals with rs2304669-CC and CT genotypes (P = 0.001). In addition, the three haplotypes containing the risk T allele of rs2304669 were identified to be associated with increased breast cancer risk. However, it was found that rs2304672, rs2070062 and rs934945 polymorphisms were not related with breast cancer risk.
  
  
  CONCLUSIONS
  The locus rs2304669 on Per2 gene is associated with breast cancer risk. Genetic variation of circadian clock genes may increase the susceptibility to breast cancer. Therefore, it may become an important biomarker of susceptibility to breast cancer.
authors.affiliation: Department of Medical Oncology, Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100021, China.
authors.forename: Wen-miao
authors.initials: WM
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Yuan
authors.forename: Jia-yu
authors.initials: JY
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Ma
authors.forename: Ying
authors.initials: Y
authors.lastname: Fan
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Pin
authors.initials: P
authors.lastname: Zhang
authors.forename: Bing-he
authors.initials: BH
authors.lastname: Xu
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics*; D056926:CLOCK Proteins / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D014644:Genetic Variation; D006801:Humans; D056950:Period Circadian Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; C421902:PER2 protein, human; D056950:Period Circadian Proteins; D056926:CLOCK Proteins; C538943:CLOCK protein, human