Identification of group'E' chromosome abnormalities in human cells.

Definite identification of the chromosome involved in E trisomy (Edward's syndrome; Edwards et al, 1960) and in various structural alterations of the 17/18 autosomes has often been difficult on purely morphological grounds (Hamerton, 1971). Autoradiographic evidence that chromosome No. 18 completes synthesis later than No. 17 (Giannelli and Howlett, 1967) and that the extra chromosome in E trisomy is similarly late-replicating (Yunis, Hook, and Mayer, 1964) has supported Patau et al (1961) in defining this chromosome as a No. 18. This evidence was further supported by the demonstration that specific damage induced by adenovirus type 12 in chromosome No. 17 is only found in two of the five 17/18 autosomes in E trisomy (McDougall, 1970). A recent report by Bobrow and Pearson (1971) described the use of fluorescent chromosome staining (Caspersson et al, 1970) in the identification of E-group autosomes, although even in this highly successful method it was not possible to differentiate No. 17 from No. 18 in every cell. The recently described method of staining chromosomes with 'Giemsa', the 'ASG' technique (Sumner, Evans, and Buckland, 1971), has also provided a system of differentiation between the 17/18 autosomes. Results are presented in this report from studies with further cases involving E-group abnormalities, in which it has been possible to identify the chromosome involved in the aberration following virus infection in vitro.