Trisomy 18
- 1 January 1969
- journal article
- Published by Radiological Society of North America (RSNA) in Radiology
- Vol. 92 (1) , 37-43
- https://doi.org/10.1148/92.1.37
Abstract
Since Tijio and Levan established the normal human chromosome number as 46, numerous abnormalities of the human chromosome complement have been described. Four reported clinical syndromes are associated with autosomal (non-sex chromosomes) anomalies. The first of these was described in 1959 by Lejeune et al., who found that in mongolism there was an extra chromosome in group 21–22 (also known as the G group). The extra chromosome presumably resulted from nondisjunction in meiosis. There is a correlation between increased maternal age and mongolism. Because of this, it is thought that in most instances the nondisjunction occurs in the ovary, particularly in an older ovary. Thus, instead of two pairs of chromosomes in the G group, mongoloids have one pair plus a triplicate set. By convention this is called “trisomy 21–22.” In 1960, Edwards et al. published the first case report of trisomy 18 (3). In this syndrome there is also a correlation between older maternal age and nondisjunction. At present over 100 ...This publication has 0 references indexed in Scilit: