Smalley's research centers on the identification of genetic factors influencing complex behavioral traits, particularly psychiatric disorders with onset in childhood or adolescence. Her laboratory is currently conducting a genome scan to identify genes underlying attention deficit hyperactivity disorder (ADHD) and is collaborating on a genome scan in autism with the International Molecular Genetic Study of Autism Consortium (IMGSAC). Her research on ADHD includes studies of treatment by gene interactions, neuropsychological deficits in ADHD, and gene by environment interactions. In addition to the identification of susceptibility genes underlying complex behavior traits, Smalley?s laboratory focuses on the development and application of statistical methods to uncover genes and gene by environment interactions that may underlie common, complex traits, such as human behavior. Her group developed a multivariate statistical approach to carry out genome scans using extremely large numbers of molecular markers or novel methods such as genomic mismatch scanning. Smalley?s laboratory recently evaluated several putative candidate genes underlying ADHD that are involved in dopamine regulation. They found evidence that the dopamine D4 receptor gene contributes a minor risk to ADHD but that in their sample of largely multiplex families, the dopamine transporter gene does not. The IMGSAC team recently identified a potential region on chromosome 7q that may harbor a susceptibility gene for autism.