ABSTRACT. Anti-scrapie breeding programs have been initiated to screen for scrapie-resistant sheep based on ovine prion protein gene (PRNP) genotypes at codons 136, 154 and 171 in many countries, especially European Union member states. However, investigation of sheep PRNP genotypes is limited in China, despite the large number of sheep breeds. We analyzed 432 sheep of five different breeds from farms in northwestern China, using PCR-single-strand conformational polymorphism analysis (PCR-SSCP); the corresponding haplotypes of different PRNP alleles were cloned. PRNP allele genotyping was done by amplification refractory mutation system-PCR (ARMS-PCR), according to the haplotype clones of each PRNP allele. The validity of ARMS-PCR was checked by PCR-SSCP. Another 325 unknown PRNP genotypes of other sheep breeds were analyzed according to the established ARMS-PCR. Genotype frequencies of 757 sheep were analyzed with these two methods to evaluate susceptibility to scrapie in northwestern China. Relevant mutations were also detected at other sites. Both methods were effective for ovine PRNP allele genotyping, and the results of the analysis completely coincided. Scrapie-resistant genotypes were found to be uncommon, indicating a high risk for ovine scrapie in northwest China. In addition to codons 136, 154 and 171, we found numerous new mutations; nearly half of them were previously unreported. These sheep populations have a high degree of polymorphism at the PRNP locus.

ABSTRACT. We carried out a hospital-based case-control study to investigate the role of XRCC1 gene Arg399Gln, Arg280His, and Arg194Trp polymorphisms in susceptibility to gastric cancer. A total of 214 gastric cancer patients and 247 control subjects were recruited between March 2013 and March 2015, and polymorphism genotype frequencies were determined by polymerase chain reactionrestriction fragment length polymorphism. Using the chi-square test, we detected statistically significant differences in age (chi-square = 22.25, P < 0.001), gender (chi-square = 6.74, P = 0.01), and family history of cancer (chi-square = 4.73, P = 0.03) between the case and control groups. Logistic regression analysis revealed that the XRCC1 Arg194Trp TT genotype conferred increased susceptibility to gastric cancer compared to the CC genotype [odds ratio (OR) = 2.38, 95% confidence interval (CI) = 1.28-4.49]. Moreover, individuals carrying the T allele of this variant were found to be at moderately increased risk of this disease (OR = 1.56, 95%CI = 1.16-2.09). However, the XRCC1 2 S. Chen et al. Genetics and Molecular Research 15 (3): gmr.15038342 Arg399Gln and Arg280His polymorphisms were shown to have no influence on the development of gastric cancer. In conclusion, we suggest that the XRCC1 gene Arg194Trp polymorphism is associated with gastric cancer susceptibility in the Chinese population.