This admirable little volume succeeds in distilling into 88 pages the essence of much of modern human genetics. Unencumbered by the mathematics of population genetics at one extreme, or the complexities of molecular biology at the other, it guides the reader carefully and lucidly through the most active area of medical science of the past few decades. It prepares him, should he have the inclination, for a more leisurely patrol along any of the fascinating side trails of this field of endeavor.
The author divides inherited diseases logically into three classes: those due to chromosomal accidents, those deriving from abnormal genes of large effect; and diseases which are thought to be polygenic in origin. He reminds us frequently that in almost all cases there is an environmental component to the expression of an error of the genetic apparatus. He also makes the point that variability in expression of inherited disease