The twin-family study is a hybrid study design, combining the strength of discriminating genes and environments (classical twin study) and identifying genes (classical family study). The "Healthy Twin Study", a family-twin study in Korea was launched ...
The twin-family study is a hybrid study design, combining the strength of discriminating genes and environments (classical twin study) and identifying genes (classical family study). The "Healthy Twin Study", a family-twin study in Korea was launched in 2005, by the support of CDC Korea, and have successfully collected 2,860 individuals of twins and their families until 2009 (5th year of the study). The study has systematically collected epidemiologic information, clinical and anthropometric measurements, and a range of biospecimens for the 2,860 participants. The epidemiologic information covers basic life style, diet and physical activity, occupation and socioeconomic status, psychosocial factors, and twin specific questionnaires such as zygosity and development history. Clinical measurements include basic biochemical tests of bloods and urines, bone density (DEXA), impedence and direct fat mass (DEXA), ECG, pulmonary functions, anthropometries and other physical examinations. High quality biological specimens were collected with informed consent for further omics studies. Genotyping with dense SNP markers (Affymetrix Genechip version 6) is undergoing for about 1,900 individuals, which will enable gene hunting studies as well as gene-environmental interaction detections. Meanwhile, we established a method to estimate zygosity both by questionnaire and genotyping (STR markers), and estimated heritability for important quantitative traits of interest. Height showed the highest heritability (0.92) and metabolic syndrome-related phenotypes showed moderate to high level of heritability ranging 0.4~0.65. The information and basic analyses accomplished will provide basis for family-based association studies and gene-environmental interaction studies of the project.