Book excerpt: This reference for lay readers and health care professionals presents information on disorders affecting fewer than 200,000 people in the U.S. at any one time. Each of the more than 1,100 entries describes the characteristics, causes, and symptoms of a particular disorder. The extensively cross-referenced volume also features profiles of 680 disease specific organizations as well as 629 umbrella organizations and 77 government agencies. Annotation copyrighted by Book News, Inc., Portland, OR