Effects of various medical and social pracitices on the frequency of genetic disorders.

The effects of a number of new medical and social practices on the incidence of genetic diseases and gene frequency have been studied. The results deal with short-term effects, since these are of most practical importance, and with the combined effects of several factors acting together. The size of any effects depends on the feasibility of the different practices and on the extent to which they are adopted by the population. Most of the practices reduce the incidence of the diseases in the next generation, but some may be dysgenic. For example, improved treatment of affected individuals in dominant and X-linked diseases could lead to improved reproductive fitness, higher gene frequencies, and to an increased incidence in future generations. However, such deleterious effects may be avoided by genetic counseling or offset by other preventive practices. In recessive disorders, a small reduction in the average fitness of carfiers detected by population screening would outweigh any deleterious effects of other practices. In general there seems to be little cause for alarm about the deleteious effects of the new medical and social practices being adopted.