[Age dependence of chromosomal findings]

Relations between aging and chromosomal aberrations are reviewed, comparing own results with those of other investigators. The increase of hypodiploidy in aging women described by Jacobs et al. 1961 could be confirmed by several authors, whereas the age dependence of the rate of hypodiploidy in men, seems to be uncertain. It can be assumed that the hypodiploidy in female cells is caused by loss of X-chromosomes. Primarily, with regard to the observation of Fitzgerald in 1975, that X-chromosomes with premature centromere division (an anomaly which seems to be associated with a high tendency to non-disjunction) could be found more frequent in old, rather than in young females. This result is confirmed by our own studies. In agreement with other investigators we were able to establish a significant difference between the rates of structural aberrations of two age groups of "normal" females: An age-dependent increase of structural aberrations in vivo, could be concluded from the fact that dicentric chromosomes were most frequent in 48-hour cultures of the old females. The high frequency of single chromatid breaks in 72-hour cultures in the same age group, led us to the assumption of an age-dependent chromosomal instability in relation to in vitro conditions. Since numerical and structural aberrations indicate mutagenic alterations, the reviewed cytogenetic results may be an important support for the mutation theories of aging.