Chromosomal breakage and scleroderma: studies in family members.

Chromosome studies were performed on 54 apparently healthy relatives of 29 scleroderma patients and on 40 controls. Increased chromosomal breakage is observed in 86 per cent of brothers and sisters and in 68 per cent of children of patients. If the findings in relatives are compared to those obtained in the 29 scleroderma patients of these families, the percentage of abnormal cells does not differ significantly between the two groups (25.8 per cent and 29.1 per cent respectively), and there is no difference for the frequencies of gaps and open breaks. However acentric fragments, "minutes" and morphologically abnormal chromosomes are significantly increased in patients as compared to their asymptomatic relatives with increased breakage. The distribution of breaks is found to be random. The presence of structural chromosome aberrations in relatives of scleroderma patients may have a special importance with regard to the concept of familial autoimmune disease.