Provides an engaging account of how genetic abnormalities, neurobiology and neuropsychology work in concert to manifest cognitive-behavioral dysfunction. The authors have woven the various molecular genetic, genomic, neurophysiological and neurobehavioral threads together into a cohesive fabric of human genes, brain, and behavior. The first section provides and introduction to neurobehavioral disorders and their phenotypes in order to investigate the pathway between genes and behavior. The second section covers autosomal disorders that produce neurobehavioral dysfunction including neurofibromatosis, Prader-Willi syndrome, and tuberous sclerosis among others. The final section considers X-linked disorders in which syndromal and nonsyndromal forms of XLMR are present. It includes the first comprehensive account of the genotype and phenotype in FRAXE, the other fragile X mutation.