Genetic Counselling

Abstract

Until the early 1960s little genetic counselling was done, and few people appreciated its value or even its need. But the situation has changed and nowadays almost every medical school and teaching hospital supports a genetic counselling unit. Before considering the problems of genetic counselling perhaps we should first be clear exactly what we mean by “genetic disease.” There are essentially three categories of genetic disease. Firstly there are the unifactorial disorders, each of which is due to a single (Mendelian) gene which may be dominant, recessive, or X-linked. Examples are given in table I. These disorders are individually rare but the risks to relatives are usually high. Secondly, there are the chromosomal disorders such as Down’s syndrome (mongolism) and certain disorders associated with male infertility (Klinefelter’s syndrome) or primary amenorrhoea (Turner’s syndrome). Thirdly, there are the multifactorial disorders which result from the effects of many genes plus environmental effects. They include many congenital malformations (anencephaly, spina bifida, hare-lip, and cleft palate), diseases of “modern society” (hypertension, coronary artery disease, peptic ulcer, diabetes mellitus), and certain psychiatric disorders (schizophrenia and probably manic-depressive psychosis). © 1975, British Medical Journal Publishing Group. All rights reserved.