Possible genetic consequences of relaxed selection against common disorders with complex inheritance.

With increasing success in medical treatment for many common disorders with complex inheritance, it is expected that the incidence of patients requiring treatment will gradually rise from generation to generation. While this is theoretically true for a long range of future, the pattern of possible increase in the frequency of a disorder resulting from complete cure has been examined with special reference to the next few generations. It was shown that the maximum possible increment will take place in the first generation, with additional increment rapidly diminishing with subsequent generations. For congenital heart disease, for example, the restoration of full fertility to all of the patients would incur an increase in the frequency at birth of the disease by about 10% after 5 to 10 generations.