Birth defects research: 1980 and after.
Very little is known about environmentally-induced birth defects, i.e., those due to exogenous agents acting directly on the fetus or indirectly through the mother. Established teratogens include some viruses, drugs, radiations and one or two industrial chemicals. Much is known about birth defects due to single-gene mutations. Knowledge is scarce, however, concerning faulty regulation of gene expression or additive effects involving multiple-gene causation of disease and defect, and almost nothing is known about the mechanisms of multifactorial (gene plus environment) defects, which probably account for the majority of developmental anomalies known to man. Impressive progress has been made in understanding and control of inborn errors of metabolism. Carrier detection, prenatal diagnosis and effective ameliorative therapy have been worked out for many types of biochemical defects, and the entry of molecular biology into the field adumbrates the coming of more definitive preventive and therapeutic measures for many birth defects. Carrier detection and prenatal diagnosis make possible prevention of important birth defects by means of reproductive control. Ethical, social and psychological problems arising in the wake of this development are not here discussed but will surely be one of the dominating issues of medicine and public health for the coming years.