A behavioral neurogenetics approach to developmental disabilities: gene-brain-behavior associations.

This review provides a discussion of behavioral neurogenetics' contribution to understanding neurodevelopmental pathways in learning and developmental disabilities. A brief overview is given of several common neurogenetic disorders with various genetic etiologies including Down syndrome, Turner syndrome, Prader-Willi syndrome, Angelman syndrome, and Tourette's syndrome. Special emphasis is placed on fragile X syndrome as representative of a newly-discovered class of genetic conditions characterized by an unstable trinucleotide repeat. A spectrum of cognitive, behavioral, and social-emotional phenotypic features associated with fragile X syndrome is examined. Also included are findings from recent neuroimaging research and a discussion of the need for the classification of symptoms on the basis of underlying genetic/medical conditions.