Genetic Heterogeneity

Abstract
IN his catalogue of mendelian characteristics of man McKusick1 lists 1545 genetically determined variations, indicating the existence of mutant genes at at least that many loci. His book is a collection of most of the human hereditary variants reported until 1967 and is the only resource of its kind available. It is an important contribution partly as a reference work, but also because it provides a comprehensive view of how much, and how little, is known about human variety. Most of the hereditary variations listed are diseases, usually rare and often involving many organ systems. In most of these diseases, . . .