TY - JOUR T1 - TIme and stage in development at which factors operate to produce mongolism AU - SOUTHWICK WE Y1 - 1939/01/01 N1 - 10.1001/archpedi.1939.01990010077006 JO - American Journal of Diseases of Children SP - 68 EP - 89 VL - 57 IS - 1 N2 - In general, it is obvious that the factor or factors that bear a direct causal relationship to a condition which is clearly apparent at the time of birth—as, according to Brousseau,1 is the case with mongolism—must operate at the time of the formation of the gametic chromosomes or subsequently, during the development of the embryo but before the time of delivery. It is believed that a knowledge of the exact time at which such factors operate would markedly facilitate progress toward an understanding of the etiology of such a condition.HEREDITARY FACTORS  If the condition is produced by genetic factors, then it should be possible to demonstrate among closely related persons who bear any given trait specific relationship configurations that would be diagnostically characteristic of such hereditary factors. The simplest and most definite of these are the various but well known forms of simple mendelian inheritance. But when clearcut SN - 0096-8994 M3 - doi: 10.1001/archpedi.1939.01990010077006 UR - http://dx.doi.org/10.1001/archpedi.1939.01990010077006 ER -