Single Nucleotide Polymorphisms in the Mitochondrial Displacement Loop and Age at Onset of Gastric Cancer

Abstract

Background It is very difficult to contain persistently high incidence and mortality rates of gastric cancer. Moreover, the age at onset of gastric cancer is becoming earlier. However, there are few studies on the prediction of the age at gastric cancer onset. Objective To investigate the relationship between single nucleotide polymorphisms (SNPs) in mitochondrial displacement loop (D-Loop) and age at gastric cancer onset. Methods A total of 150 patients with confirmed gastric cancer by pathologically examination of biopsy samples taken during gastroscopy were recruited from Department of Gastroenterology, the Fourth Hospital of Hebei Medical University between July 2007 and December 2008. PCR was used to amplify the targeted fragment of peripheral blood mitochondrial DNA, and the mitochondrial D-Loop region was sequenced. Survival curves for patients with different ages of onset of gastric cancer were plotted by the Kaplan-Meier method, and compared by the Log-rank test. Cox regression analysis was used to identify factors associated with age of onset of gastric cancer. Results The age of onset of patients with different degrees of education was statistically significant (P<0.05) . Log-rank test revealed that patients with 153G genotype had earlier age of onset of gastric cancer than did those with 153A genotype〔 (48.0±5.3) vs (60.1±0.8) 〕 (χ2=7.757, P=0.005) . Multivariate Cox regression analysis indicated that the 153A/G polymorphism in mitochondrial D-Loop was a predictor of age at onset of gastric cancer〔HR=0.323, 95%CI (0.140, 0.745) , P=0.008〕. Conclusion The 153A/G polymorphism in mitochondrial D-Loop may be used as a novel predictor of the age at onset of gastric cancer. Analyzing the SNPs in mitochondrial D-Loop may contribute to early identification of gastric cancer.

Keywords

• stomach neoplasms|dna, mitochondrial|d-loop|polymorphism, single nucleotide|age of onset|sex factors