The amount of hereditary disease in human populations

SUMMARY The frequencies of occurrence of various types of genetic disease have been derived for a number of successive annual birth cohorts from a well‐defined geographic region with a current population in excess of two million people. The results indicate that about 9·4 individuals out of every 100 liveborn will have serious genetic diseases or handicaps and that another 2·7 persons out of every 100 born alive suffer from disorders of unknown aetiology. However, the incidence of simple, dominant conditions is probably very close to 8 in every 10,000 liveborn, or about 12 times lower than previously believed. Accordingly, estimates of the risk to human health from these diseases, due to an artificially induced increase in mutation rate in man, may be some 12 times too high.