In his preface, Dr Nyhan states that the purpose of the book is "to provide material of practical benefit to the physician in the diagnosis and management of genetically determined disease." The book grew out of the authors' collected experience with a wide variety of genetic disorders; in essence, they have given us reviews of the literature expanded by their own cases and families and illustrative case reports. The emphasis is on the clinical presentation, differential diagnosis, and workup of the patient that will efficiently lead to diagnosis and management. The mode of inheritance is described, and there is a sufficient amount of biochemical information to enable the clinician to appreciate the nature of the basic defect without being intimidated by detail. The black-and-white illustrations are generally of high quality and appropriately plentiful. Some, such as the photographs of xanthomas and other skin lesions, would have benefited from color.