Association between obesity and DNA methylation among the 7-16 year-old twins / 中华流行病学杂志

Objective: On whole-genome scale, we tried to explore the correlation between obesity-related traits and DNA methylation sites, based on discordant monozygotic twin pairs. Methods: A total of 90 pairs of 6-17 year-old twins were recruited in Chaoyang district, Yanqing district and Fangshan district in Beijing in 2016. Information on twins was gathered through a self-designed questionnaire and results: from physical examination, including height, weight and waist circumference of the subjects under study. DNA methylation detection was chosen on the Illumina Human Methylation EPIC BeadChip. R 3.3.1 language was used to read the DNA methylation signal under quality control on samples and probes. Ebayes function of empirical Bayes paired moderated t-test was used to identify the differential methylated CpG sites (DMCs). VarFit function of empirical Bayes paired moderated Levene test was used to identify the differentially variables CpG sits (DVCs) in obese and normal groups. Results According to the obesity discordance criteria, we collected 23 pairs of twins (age range 7 to 16 years), including 12 male pairs. A total of 817 471 qualified CpG loci were included in the genome-wide correlation analysis. According to the significance level of FDR set as <0.05, no positive sites would meet this standard. When DMC CpG site cg05684382, with the smallest P value (1.26E-06) as on chromosome 12, the DVC CpG site cg26188191 with the smallest P value (6.44E-06) appeared in CMIP gene on chromosome 16. Conclusions: In this study, we analyzed the genome-wide DNA methylation and its correlation with obesity traits. After multiple testing corrections, no positive sites were found to have associated with obesity. However, results from the correlation analysis demonstrated sites cg05684382 (chr: 12) and cg26188191 (chr: 16) might have played a role in the development of obesity. This study provides a methodologic reference for the studies on discordance twins related problems.

Effect of family environment in childhood and adolescence on mental health in adulthood / 中华流行病学杂志

Objective: To explore the relationship of family environment in childhood and adolescence and mental health in adulthood. Methods: A total of 791 subjects aged ≥25 years were selected through the Chinese National Twin Registry (CNTR). The short-form of Family Environment Scale-Chinese Version (FES-CV) was used to evaluate the family environment during childhood and adolescence in three dimensions: relationship, system maintenance and personal growth. The mental health status in adulthood was assessed with the Chinese version of 6-item Kessler Psychological Distress Scale (K6). The generalized linear mixed model was used to examine their relationship. Results: About 4.6% of the subjects reported general or worse mental health status. Compared with the subjects with good mental status, statistical difference was observed only in parenting way among twins (living together or not). After adjusting the potential confounders, such as age, sex, zygosity, education and lifestyle (smoking, drinking and physical activity), good family relationship and system maintenance had a positive effect on mental health, with the OR (95%CI) of 0.66 (0.51-0.87) and 0.70 (0.50-0.98) respectively. Furthermore, parenting way did not modify the effect of family environment on mental health status in adulthood (interaction: P>0.05). In each scale, scores of cohesion and organization were positively correlated with mental health, while the score of conflict was negatively correlated with the mental health. Conclusion: Good family relationship and system maintenance in childhood and adolescence had a positive impact on mental health in adulthood.

Fujian Tulou Family Cohort Study: study design and characteristics of participants and pedigrees in baseline investigation / 中华流行病学杂志

Objective: To describe the study design, the characteristics of participants as well as the pedigrees included in the baseline survey of Fujian Tulou Family Cohort Study. Methods: Fujian Tulou Family Cohort Study was a prospective open cohort study with a biological sample bank. A baseline survey was conducted in Tulou areas of Nanjing county in Fujian province from 2015 to 2018, including questionnaire survey, physical and biochemical indicators examinations, and blood sample collection in adults aged ≥18 years. In addition, family relationship of the participants was also recorded. The pedigree information of the juveniles under 18 years old were also collected. Results: The baseline survey included 2 727 individuals in two clans, of whom 2 373 (87.0%) were adults, and 2 126 participants completed questionnaires, physical examinations and biochemical tests. The average age of the 2 126 participants was (57.9±13.3) years, with 39.4% being males. The current smoking rates in male and female participants were 41.2% and 2.1%, respectively. The corresponding rates of current alcohol consumption were 19.0% and 2.6%. For common chronic diseases, the prevalence rates were 51.3% for hypertension, 9.7% for diabetes and 26.7% for hyperlipemia according to the self-reported disease diagnoses, health examination results and biochemical examination results in class Ⅱ or Ⅲ hospitals. Based on the family relationship information and genealogical data, 710 pedigrees were finally identified, consisting of 5 087 family members. The numbers of five, four, three, and two generations pedigrees were 3, 88, 238 and 381, respectively. The pairs of the first to the fifth degree relatives were 12 039, 2 662, 1 511, 202 and 31, respectively. Conclusion: The establishment of Fujian Tulou Family Cohort provides valuable resources for exploring the genetic risk factors, environmental risk factors and gene-environment interactions contributing to the risk of common chronic diseases.