29 The Distribution of Chromosome Aberrations in Time: Chromosome Studies in Newborn and Spontaneous Abortion Populations

Abstract

In a 36 month period involving 9000 newborns, three clusterings of autosomal chromosomal trisomies were recognized. Using the last menstrual period for estimating time of conception, the first cluster extended from October through December, 1963, and included 3 cases; the second cluster, June and July, 1964, 3 cases; and the third cluster, December, 1964 through June 1965, 5 cases. In the remaining 24 months, only 2 other cases were observed. Retrospective studies for the first cluster revealed: 1. 8 additional trisomies in nearby Chicago hospitals; 2. a significant increase in the number of stillbirths and conceptions that expired with congenital malformations at Michael Reese Hospital; 3. a similar clustering of chromosome abnormalities in newborns in Denver, Colorado (PUCK and ROBINSON, Science [1965]) and in spontaneous abortions in London, Ontario (CARR, personal communication). For the second cluster there was a corresponding increase in the abortion population in Canada. There was no statistically significant increase in the reported incidence of 9 infectious diseases including rubella or infectious hepatitis, relative to the three clusterings defined in the newborn population. Prospective studies on the distribution of chromosome aberration in time have been conducted since November, 1964, and reveals that when the spontaneous abortion and newborn populations are considered as one conceptual population, the distribution of chromosome aberrations in time appears random. These findings indicate that either the factors responsible for nonrandom distribution of chromosome aberrations were not operating during the time period covered or that onrandom distribution of chromosome aberrations does not occur in the human population. (APS)