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Background: Recent studies relating to the association between DNA repair-gene polymorphisms and colorectal cancer risk would, to the best of our knowledge, appear to be very limited. This study was designed to examine the polymorphisms associated with three DNA repair genes, namely: XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln, and investigate their role as susceptibility markers for colorectal cancer.

ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with "power/sprint" performance in other sports.

Studies have shown that the 577R allele of α-actinin-3 (ACTN3) is more prevalent in sprint athletes than in the general population or in endurance athletes. We examined the distribution of ACTN3 R577X (rs 1815739) genotypes and alleles in the Taiwanese general population (603) and in elite sprint swimmers who had participated in international/national events (168). Additionally, 50 pre-adolescent (age 11-13 years) male students and 38 adult males who completed 12-weeks of swimming training, were included in the present study. We found that the frequencies of the R allele were significantly higher in female international sprint swimmers (67.6%) than in national sprint swimmers (50.0%) or in the general population (53.7%). The 25-m performance was significantly improved across the genotypes after swimming training among the pre-adolescent males but not among the adult males. In addition, pre-adolescents with the RR genotype had the best performance both before and after training although not statistically significant. In conclusion, the frequencies of ACTN3 577R allele were significantly higher in female international sprint swimmers than among national sprint swimmers or the general population. Furthermore, male pre-adolescents with either the ACTN3 RX or XX genotype showed a greater improvement in 25-meter swimming performance than those with the RR genotype.

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The relationship between diet and colorectal cancer has been previously demonstrated and supported with strong epidemiological evidence. The role of genetic polymorphisms has, however, been less well elaborated upon. We conducted a hospital-based case-control study including 727 cases and 736 healthy controls to evaluate the associations of the polymorphic phase-I and -II biotransformations (CYP1A1, CYP1A2, GSTM1, GSTT1, GSTP1, NAT1 and NAT2) and DNA-repair enzymes (XRCC1, XRCC3 and XPD) with the risk of contracting colorectal cancer. We found that men featuring the CYP1A1*2C G/G genotype, the GSTT1 null genotype and XPD 751 with the Gln allele were associated with an elevated risk of colorectal cancer than were men who did not exhibit such genetic features. Multivariate logistic regression analysis revealed that individuals featuring more than two high-risk genotypes increased the colorectal-cancer risk 3.1-fold (OR = 3.1, 95% CI = 1.8-5.2). For women, subjects featuring the CYP1A1*2C G/G genotype and the XRCC3 Thr/Thr genotype faced a 3.1-fold greater risk (95% CI = 1.3-7.0) of colorectal cancer when compared to those featuring the CYP1A1*2C A allele and the XRCC3 Met allele. Taken together, this study suggests that polymorphisms of genes involved in biotransformation and DNA repair could modulate colorectal-cancer risk in Taiwan.

This study suggests that the GSTT1 gene can modulate the colorectal cancer risk and vegetable/fruit-related colorectal cancer risk, particularly in men of no smoking history.