[Improvement on PCR-CTPP: a SNP genotyping approach based on mismatch technique].

To explore the technique principle of PCR with confronting two-pair primers (PCR-CTPP) and improve the accuracy of SNP genotyping by taking the 1298 locus of human gene MTHFR as an example, the reliability between conventional PCR-CTPP and improved PCR-CTPP was compared using reconstructed PCR-CTPP detecting system in terms of designing appropriate primers and optimizing annealing temperature and the final concentration of primers. The improved PCR-CTPP detection system proved to be more accurate, which supported the viewpoint on the theoretical defects of conventional PCR-CTPP. The large-scale study verified the reliability of the improved method. It is expected that this improved technique would be widely used in the field of medicine and molecular biology.

[Influential factors of Hardy-Weinberg equilibrium on the study of association between gene polymorphism and disease].

OBJECTIVE: According to the data collected from gastric cancer families comparative study, the influence factors of Hardy-Weinberg (H-W) equilibrium in the association studies of gene polymorphism and disease were analyzed to reveal the reasons that affecting the equilibrium deviation in the group. METHODS: Varieties of risk genotype for gastric cancer were analyzed and detected with H-W equilibrium, genetic linkage disequilibrium analysis and Cochran-Armitage trend test. RESULTS: (1) Significant deviations from H-W equilibrium were observed in IL-1B-31, IL-1B-511, IL-1RN and TNF-A-308 of the cases and controls (P < 0.01). MIF-173 tended to be equilibrium in the population. (2) Deviations from expectations of phenotypes combination probability were observed in two-site H-W chi(2) tests (P < 0.01). (3) The Cochran-Armitage trend test showed that distribution of IL-1B-511 and IL-1RN were significantly different (P < 0.05), suggesting that population stratification might have existed in the group. CONCLUSIONS: (1) Affected by frequency-dependent selection, under the combination of linkage disequilibrium, mutations and interaction, genotype frequency of IL-1B-31, IL-1B-511, IL-1RN and TNF-A-308 showed deviation from H-W equilibrium in population. (2) Two-site genetic equilibrium test model seemed better to reflect the differences of phenotypic combination fitness. (3) Population stratification was another factor to express the deviation from H-W equilibrium.