Cytogenetic studies in leucocytes on the general population: subjects of ages 65 years and more

No results have yet been published of cytogenetic studies on a random sample of the general population. Such studies, however, are desirable for a number of reasons. First, Jacobs, Court Brown & Doll (1961), Jacobs et al. (1963) have reported finding an increase in the number of aneuploid cells with age in blood cultures from apparently normal individuals. These studies were made on a non-randomly selected group of individuals, and it is desirable to see whether the same effect is present in a randomly chosen group of subjects. Secondly, it is usual for small numbers of cells in blood cultures from normal individuals to contain structural abnormalities of the chromatid or chromosome type. It is known that the proportion of cells with chromosomal abnormalities can be markedly increased in blood cultures following exposure in wiwo to high doses of radiation (Tough, Buckton, Baikie & Court Brown, 1961 ; Bender & Gooch, 1962, 1963 ; Buckton, Jacobs, Court Brown & Doll, 1962). In theory it may be anticipated that some increase will follow exposure to low doses, and the search for such an effect will be helped by knowledge of the frequency of cells with structural abnormdities in a sample of the general population. Thirdly, it has for some time been known that, occasionally, variations occur in the morphology of the acrocentric chromosomes and chromosome no. 16, and it is of interest to determine the frequency of these phenomena (Sasaki, Makino & Kajii, 1963; Chandra & Hungerford, 1963; Chapelle, Aula & Kivalo, 1963). Finally, there have been a number of reports tending to associate apparently minor chromosomal abnormalities with pathological states (Tough et al. 1962; Gunz, Fitzgerald & Adams, 1962; Schmid, 1962). Some of these reported associations, however, may be fortuitous, and an important aid to determining whether this is so will be the study of the frequency of minor abnormalities and variations in the general population. This communication reports the results of the study of 189 elderly subjects who were randomly chosen from the general population, and for whom leucocyte cultures have been examined. Particular emphasis has been laid on three kinds of investigation, the distribution of chromosome counts, the frequency of cells with chromatid and chromosome structural abnormalities, and the frequency of subjects with abnormalities or with well-marked variations of the karyotype in all their cells. MATERIAL AND METHODS During 1961 and 1962 the staff of the Edinburgh Geriatric Hospital Service studied the medical status and social welfare of a random sample of subjects of ages 65 years and more drawn from the lists of three general practices. One was a rural practice outside Edinburgh and two were urban practices within Edinburgh. The opportunity was taken to undertake chromosome