BackgroundMost diseases are thought to arise from interactions between environmental factors and the host genotype. To detect gene–environment interactions in the development of lifestyle-related diseases, and especially cancer, the Japan Multi-institutional Collaborative Cohort (J-MICC) Study was launched in 2005.MethodsWe initiated a cross-sectional study to examine associations of genotypes with lifestyle and clinical factors, as assessed by questionnaires and medical examinations. The 4519 subjects were selected from among participants in the J-MICC Study in 10 areas throughout Japan. In total, 108 polymorphisms were chosen and genotyped using the Invader assay.ResultsThe study group comprised 2124 men and 2395 women with a mean age of 55.8 ± 8.9 years (range, 35–69 years) at baseline. Among the 108 polymorphisms examined, 4 were not polymorphic in our study population. Among the remaining 104 polymorphisms, most variations were common (minor allele frequency ≥0.05 for 96 polymorphisms). The allele frequencies in this population were comparable with those in the HapMap-JPT data set for 45 Japanese from Tokyo. Only 5 of 88 polymorphisms showed allele-frequency differences greater than 0.1. Of the 108 polymorphisms, 32 showed a highly significant difference in minor allele frequency among the study areas (P < 0.001).ConclusionsThis comprehensive data collection on lifestyle and clinical factors will be useful for elucidating gene–environment interactions. In addition, it is likely to be an informative reference tool, as free access to genotype data for a large Japanese population is not readily available.

Background and Aim: The question of whether fatty liver might predict impaired fasting glucose or type 2 diabetes mellitus in a longitudinal manner was assessed in Japanese subjects undergoing a health checkup. Methods: A total of 12 375 individuals (6799 men and 5576 women) without hyperglycemia or type 2 diabetes mellitus in 2000 and participating in 2005 were included. Multiple logistic regression analyses were performed for both sexes, adjusted for age, body mass index, elevated blood pressure or hypertension, family history of diabetes mellitus, alcohol drinking and smoking. Results: Impaired fasting glucose and type 2 diabetes mellitus were newly diagnosed in 7.6% and 1.0% of men and 3.8% and 0.5% of women, respectively, within the 5-year period. The prevalence of newly diagnosed impaired fasting glucose and type 2 diabetes mellitus was significantly higher in the participants with fatty liver than without fatty liver in both sexes. Fatty liver adjusted for the other factors was thus a risk factor for impaired fasting glucose and/or type 2 diabetes mellitus in both sexes (men odds ratio [OR] 1.91, 95% confidence interval [CI] 1.56-2.34 and women OR 2.15, 95% CI 1.53-3.01). The impact of fatty liver was stronger among the participants with a lower body mass index (men OR 0.92, 95% CI 0.86-0.99 and women OR 0.90, 95% CI 0.81-0.99, for one increment of body mass index). Conclusion: Fatty liver is an independent risk factor for impaired fasting glucose and type 2 diabetes mellitus, having a stronger impact in those Japanese with a lower body mass index undergoing a health checkup.

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The question of whether alcohol drinking is a risk factor for fatty liver as shown by ultrasonography was investigated by both cross-sectional and longitudinal approaches in Japanese undergoing a health checkup. In this cross-sectional study, 32,438 males (49.0 +/- 11.9 years old) and 31,009 females (48.2 +/- 11.6 years old) receiving a health checkup from 2000 to 2005 were included. Longitudinally, 5,444 males (49.8 +/- 10.7 years old) and 4,980 females (50.4 +/- 9.3 years old) participating in both 2000 and 2005 were included. Multiple logistic regression analyses were performed for both sexes, adjusted for age, BMI, and smoking. The prevalence of fatty liver in non-, occasional, daily moderate, and daily heavy drinkers was 28.5, 27.5, 18.7, and 19.1% in men and 12.4, 7.7, 5.4, and 6.7% in women, respectively (inverse association, P < or = 0.05 for both). Occasional, daily moderate, and daily heavy drinking in men and occasional and daily moderate drinking in women were inversely associated with fatty liver in the cross-sectional study. Daily moderate and heavy drinking appeared protective in men in the longitudinal study. Alcohol drinking may not be a major risk for fatty liver in Japanese undergoing a health checkup.

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