The case we wish to report is the occurrence of Mongolian imbecility in one of twins, the normal child being distinctly above the average in intelligence. Since twins are subject to identical conditions from conception to birth, and usually enjoy practically the same environment until adolescence, the rare occurrence of Mongolism in one of them permits certain inferences relative to the etiology of this form of feeblemindedness. A brief résumé of the more pertinent facts concerning Mongolian feeblemindedness is appended, together with a review of the literature of Mongolism in twins.
RÉSUMÉ OF MONGOLISM
One of the most clearly defined and best known types of feeble-mindedness is that first designated as the Mongolian, Kalmuc or Tartar variety by J. D. Langdon Down1 in 1866, so called from their facial resemblance to members of the Mongolian race. Tredgold2 states that with the possible exception of the tongue, there
HAROLD SWANBERG, H. A. HAYNES. A CASE OF MONGOLISM IN ONE OF TWINS. Arch NeurPsych. 1919;1(6):717–725. doi:10.1001/archneurpsyc.1919.02180060054003