Skeletal anomalies in trisomy 21 as an example of amplified developmental instability in chromosome disorders: Histological study of the feet of 21 mid‐trimester fetuses with trisomy 21

Abstract

In a previous radiographic study on the feet of 71 adults with trisomy 12 we found, in comparisn to control individuals, an increased prevalence of biphalangeal toes and metatarsophalangeal sesamoid bones. The present histological study on the feet of 21 mid‐trimester fetuses with prenatally diagonosed trisomy 21 confirms results of the earlier study. At both stages of development these minor bone anomalies have about the same frequency, thus suggesting 1) that they are selectively neutral, and 2) that they reflect a basic (innate) failure of ordered morphogenesis. Our observation that the normal spatial pattern skeletal variants is reproduced in trisomy 21 simply on a quantitavely higher level lends sound support to the hopothesis of amplified developmental instability in chromosome trisomies.