Book Review Medical Genetics. Edited by Victor A. McKusick, M.D.; and Robert Claiborne (senior editor). 320 pp., illustrated. New York: Hospital Practice Publishing Company, 1973. $13.95. Genetics in Medicine , 2nd edition. By James S. Thompson, M.D.; and Margaret W. Thompson, Ph.D. 400 pp., illustrated. Philadelphia: W.B. Saunders Company, 1973. $9.00.