Longitudinal Twin Study of Reading Disability (LTSRD; DC 005190; S.J.Wadsworth, PI; DeFries, Olson & Willcutt, co-Investigators; http://ibg.colorado.edu/rdf/). This is the first longitudinal study of reading disability using genetically informative data from participants specifically selected for reading difficulties. The purpose of this study, funded by the National Institute on Deafness and Other Communication Disorders (NIDCD; DC 005190), is to provide new information about the causes and consequences of stability and change in reading disability and its dimensions/subtypes, as well as about long-term comorbidity and covariation of reading disability with other abilities (e.g., specific cognitive abilities, language and perceptual processes), ADHD and other psychopathology.
Longitudinal Twin Study of Early Reading Development (ILTS; HD- 038526; R.K. Olson, PI; Byrne, Corley, DeFries, Keenan, Pennington, Wadsworth, and Willcutt, co-Investigators; http://ibg.colorado.edu/rds/ ), a longitudinal study of twins, beginning at preschool age 4, and continuing through grade 4. The data from the Colorado twin sample is being combined with data from a sample of Australian twins from a parallel study (B. Byrne, PI) as well as with data from a Scandinavian sample (S. Samuelsson, PI). This unique cross-cultural, genetically-informative data set will enable us to address a broad range of questions regarding the precursors of individual differences in early reading development, as well as the etiologies of reading development from preschool through the early grades.
Etiology of Reading Disabilities and Comorbid ADHD (HD 047264; E.G. Willcutt, P.I.; DeFries, Olson. Wadsworth, Ehringer, Smolen, Stallings, Corley, Chhabilda, co-Investigators) is conducting a genome-wide screen for quantitative trait loci that increase risk for reading disability and ADHD, using data from the largest sample of siblings with RD ascertained to date . This study provides the opportunity to conduct more definitive linkage, association, and candidate-gene studies of RD, ADHD and their comorbidity than has previously been possible.
Colorado Adoption Project (CAP; HD 010333; S. J. Wadsworth, PI; DeFries, Corley, Stallings, Reynolds, & Petrill, co-Investigators; http://ibg.colorado.edu/cap/ ). The broad purpose of the CAP is to investigate the genetic and environmental etiologies of individual differences in behavioral development in the context of a longitudinal prospective "full" adoption, sibling, and twin study.
Nature, Nurture and Social Demography (NNSD; HD- HD 036773; M. C. Stallings, PI; DeFries, Corley, & Wadsworth, co-Investigators; Plomin, Hofer and Shanahan, subcontract PIs.) Investigates familial influences on educational attainment, determinants of union- and family-formation choices of young adults, and how the quality of early family relationships shapes adult child-parent relationships.
