Bivariate models for co-aggregation of dichotomous traits in twins.
The study of twins is widely used for research into genetic and environmental influences on human traits. Study designs in which independent samples of monozygotic and dizygotic twins are compared with respect to their similarity have focused on single binary trait. However, the risk of co-occurrence of more than one disease in twins is a parameter of interest to genetic epidemiologists and other investigators. For example, they may be interested in assessing the genetic and environmental etiologies of reading deficits (RD) and attention deficit hyperactivity disorder (ADHD) and their co-morbidity. In this paper, we present statistical methodology for the estimation of twin similarity with respect to two dichotomous traits measured on each member of the twin pair. For two sample problems, several test procedures that account for the correlation between twins and the correlation between traits are presented. An example based on the Australian population-based twin registry published data is given to illustrate the methodology.
Department of Epidemiology and Biostatistics, Schulich School of Medicine, University of Western Ontario, London, Ont., Canada N6A 5C1. shoukri@kfshrc.edu.sa
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D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000235:genetics / Q000276:immunology; D001315:Australia / Q000453:epidemiology; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D009010:Monte Carlo Method; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology / Q000235:genetics / Q000276:immunology; D018433:Twin Studies as Topic / Q000379:methods*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic