Chromosomal instability in collagen disease.

Chromosome instability is observed in patients with collagen disease. It is due to the presence of a chromosome-breaking agent in the serum which also induces chromosome breaks and rearrangements in blood cultures from healthy subjects. It is not possible to say at present whether this breakage factor is identical to that in patients with progressive systemic sclerosis, lupus erythematosus or rheumatoid arthritis. In all three diseases the agent is a substance with a low molecular weight between 1000 and 10,000 daltons. Since the enzyme superoxide dismutase has an anticlastogenic protective effect, the action of the agent on chromosomes is probably an indirect one, namely by generation of oxygen-dependent free radicals such as O2- x and OH.