Identifies the genetic and behavioral characteristics of nine mental retardation syndromes. Gives in-depth information on genetic causes, prevalence, and physical and medical features of Down, Williams, fragile X, and Prader-Willi syndromes, and describes their cognitive profiles, speech and language issues, and adaptive and maladaptive behaviors. Also looks at five lesser-known disorders: velocardiofacial syndrome, Rubenstein-Taybi syndrome, Smith-Magenis syndrome, Angelman syndrome, and 5p (cri du chat) syndrome. Includes bw photos of facial features characteristic of different syndromes. Dykens teaches child and adolescent psychiatry at the University of California-Los Angeles. Annotation c. Book News, Inc., Portland, OR (booknews.com)