CHARACTERIZATION OF HUMAN CHROMOSOMAL CONSTITUTIVE HETEROCHROMATIN

Our results are presented in Table I. A different variability of centromeric hetero­chromatin of chromosomes 1, 9 and 16 was observed. Quite a low variability was found in chromosome 16, while chromosomes 9 and 1 showed a high degree of variability, which was more accentuated in chromosome 9 than in chromo­some 1. In all four groups of persons there was a similar pattern of variability with the only exception mentioned below. On the whole, band 1q12 was either enlarged or diminished, while band 9q12 was most frequently enlarged. Pericentric inversions were observed very rarely and only on chromosome 9. The only exception was found in the nearest relatives of children with abnor­mal phenotype and karyotype: an unusually narrow band 1q12 was frequently detected, often onboth members of the chromosomal pair. The study is to be continued.