ETIOLOGY OF MONGOLISM

Abstract

A PREVIOUS study of mongolism showed the condition to originate between the sixth and ninth weeks of fetal life.¹The evidence to be presented here supports this conclusion. It further indicates that the causative agents related to mongolism are relatively numerous, and that the changes effected by these agents in the placental circulation are limited in number and exert their action on the host (embryo) at about the eighth week of gestation. The proof is both epidemiologic and teratologic. All available data have been summarized in order to compare the inferences derived from the one line of reasoning (epidemiologic) with those derived from the other (teratologic). <h3>EPIDEMIOLOGY</h3> <i>Incidence and Prevalence</i>.—The relative frequency of mongoloid as compared to normal infants at the Boston Lying-in Hospital during the years 1931 to 1944 was determined by Beidleman²to be 3.4 per thousand live births. From this sampling of some 14,000 births occurring over a thirteen year