Abnormal chromosomes and number 1 heterochromatin variants revealed in C-banded preparations from 13 bladder carcinomas.

The chromosomes of 13 carcinomas of the bladder were studied in C- and G-banded preparations. Heteromorphism for the amount of centromeric heteromorphism on the no. 1 chromosomes was apparent in eight tumours, and in three of these the heteromorphism was also found in the patient's normal cells. In four tumours, there were pericentric inversions of the heterochromatic regions of one or more no. 1 chromosomes. Major structural changes involving no. 1 chromosomes appeared to have occurred in at least seven of the tumours. In addition to the high incidence of heterochromatin variants (known or presumed to be constitutional phenomena), and major structural changes involving the no. 1 chromosomes, a further feature, common to four tumours, was the presence of a heterochromatic minute.