Advances in Twin and Sib-Pair Analysis.

Abstract

This book is a useful reference for both the researcher new to the field of twin and sib-pair studies and the seasoned researcher seeking a convenient single source of information about many issues related to this type of research. The book begins with a thorough review of the history of twin and sib-pair studies. The historical review is followed by a chapter that outlines various study designs and the advantages and disadvantages associated with them. Next, the experiences obtained from conducting one of the largest twin studies, the Finnish Twin Cohort, are discussed. There is also a chapter on conducting twin studies in developing countries, which discusses the advantages and pitfalls involved in undertaking such research. Additionally, the chapter discussing the generalizability of twin studies and the assumptions underlying them concisely summarizes the major criticisms of twin studies and the evidence refuting them. These chapters provide a solid introduction to twin and sib-pair studies, one that would benefit anyone thinking about embarking on such research for the first time.For the researcher already conducting a twin and/or sib-pair study, the methodology chapters offer both basic information regarding methods of analysis—introducing such concepts as concordance rates and the estimation of genetic variance—and more advanced concepts, such as dealing with gene-by-environment and gene-by-gene interactions. Modeling the effects of age and survival analysis methods as they apply to twin and sib studies are additional advanced concepts that are nicely dealt with.However, perhaps the most appealing chapters to the researcher involved in twin and/or sibling studies are those dealing with the use of such studies for mapping the genetic loci underlying complex traits. Current methods of association and linkage analysis are summarized, and advances, such as the power of multivariate analysis, are presented. There is also a chapter on how to extend the twin and sibling models of genetic variance, which are introduced earlier in the book and are implemented in the program Mx, to performing such analyses of molecular data. Finally, the utility of twins in the field of pharmacogenetics is discussed.