title: A logistic regression based extension of the TDT for continuous and categorical traits.
abstract: The transmission disequilibrium test (TDT), designed as a test of linkage in the presence of association (i.e. linkage disequilibrium), has received considerable attention in the recent statistical genetics literature due to its advantages over other within-family analytic methods. One limitation of the conventional TDT is its application solely to linkage disequilibrium between a genetic marker and a single categorical trait (e.g. presence or absence of a disease). In this paper, we present an extension of the TDT using logistic regression to examine the relation between a candidate gene or genetic marker and one or more continuous or categorical explanatory variables. This logistic regression extension of the TDT possesses all of the desirable features of the conventional TDT, as well as many advantages associated with traditional regression analysis. We describe the model and its properties, as well as a number of its possible applications, and apply it to examine linkage disequilibrium between the dopamine receptor D2 gene (DRD2) and symptoms of childhood attention deficit hyperactivity disorder (ADHD). We also briefly compare the logistic regression TDT to other quantitative TDTs that have been proposed in the literature, and highlight the advantages of a regression-based approach for examining the relation between a candidate gene and one or more continuous or categorical traits. Given its features, we regard the logistic regression extension of the TDT as a flexible new data analytic method with extensive potential applications to problems in medical, psychiatric, and behavioral genetics.
authors.affiliation: Department of Psychology, Emory University, Atlanta, GA 30322, USA. psyiw@emory.edu
authors.forename: I D
authors.initials: ID
authors.lastname: Waldman
authors.forename: B F
authors.initials: BF
authors.lastname: Robinson
authors.forename: D C
authors.initials: DC
authors.lastname: Rowe
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics; D002648:Child; D005260:Female; D006801:Humans; D015810:Linkage Disequilibrium; D016015:Logistic Models; D008297:Male; D008957:Models, Genetic; D017448:Receptors, Dopamine D2 / Q000235:genetics
chemical_list: D017448:Receptors, Dopamine D2