Constitutive heterochromatin polymorphisms in patients with malignant diseases.

The frequency of constitutive heterochromatin heteromorphisms was assessed in peripheral blood cultures of 23 patients with various malignant diseases and in their respective controls, formed by cancer-free same sex siblings of the propositi. The results showed no significant differences between the cancer and the control groups, except for chromosome 1 in breast cancer, where polymorphisms were more frequent in the controls than in the patients. Our results do not support previous data reported by others, and although there are differences in the type of malignancies studied by us and them, we believe that our control group is a more appropriate one for this particular type of study.