IMPORTANCE OF ASSOCIATION OF SATELLITED CHROMOSOMES

It has been postulated that the association of satellited chromosomes is of aetiological interest with respect to chromosomal aberrations. For this reason an investigation was carried out to determine its frequency in blood cultures of healthy adult persons, in nonmongoloid children and in mongoloid children with trisomy 21. The mean of 45 cultures of 15 healthy male probands was 32,6±14,7 associations per 100 mitoses; that of 15 healthy female probands 39,2±12. Variance analysis proved the considerable standard deviation to be mostly due to individual than to differences between parallel cultures of a given proband. In several instances the determinations were repeated which showed that the frequency of associations of satellited chromosomes appears to be individually specific and relatively stable. The frequency is being influenced by the methods of culturing. The mean out of 10 male mongoloid children was found to be 49,5±18,6 associations per 100 mitoses; 10 female mongoloid children showed a frequency of 58,9±16,9. In 15 non-mongoloid children with an age distribution similar to that of the mongoloid cases the mean out of 30 cultures was 27,2±15,3 associations per 100 mitoses. The difference between the means of mongoloid and non-mongoloid children appears to be significant (P<0,001); the augmented number of chromosomes in trisomy 21 (plus one) has been properly considered. Besides this, the variability of the different patterns of associations have been calculated. In all groups the obtained values of distribution deviated significantly from the ones to be expected: there was a constant decrease in D-D and an increase in G-G association patterns. The G-chromosome seemed to have greater tendency toward association than the chromosomes of group D. The findings, their possible aetiology and their implications are being discussed. © 1969 Springer-Verlag.