1Department of Epidemiology, Johns Hopkins Bloomberg Schoolof Public Health, Baltimore, MD, USA. email@example.com 2Department of Preventive Medicine, Seoul National UniversityCollege of Medicine, Seoul, Korea. 3Department of Preventive Medicine and Public Health, YonseiUniversity College of Medicine, Seoul, Korea. 4Institute for Health Promotion, Graduate School of PublicHealth, Yonsei University, Seoul, Korea.
Received: 1 April 2008; Accepted: 23 May 2008.
Family-based designs are commonly used in genetic association studies to identify and to locate genes that underlie complex diseases. In this paper, we review two examples of genome-wide association studies using family-based cohort studies, including the Framingham Heart Study and International Multi-Center ADHD Genetics Project.
We also review statistical methods of family-based designs, including the transmission disequilibrium test (TDT), linkage analysis, and imprinting effect analysis. In addition, we evaluate the strengths and limitations of the family-based cohort design. Despite the costs and difficulties in carrying out this type of study, a family-based cohort study can play avery important role in genome wide studies. First, the design will be free from biases due to population heterogeneity or stratification.
Moreover, family-based designs provide the opportunity to conduct joint tests of linkage and association. Finally, family-based designs also allow access to epigenetic phenomena like imprinting. The family-based cohort design should be given careful consideration in planning new studies for genome-wide strategies.
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