Mitochondrial and other tissue antibodies in relatives of patients with primary biliary cirrhosis.

Clinical and immunological studies were made on 126 close relatives of twenty-seven patients with primary biliary cirrhosis and in healthy controls matched with them for age and sex. In each of two families there were two members with overt chronic liver disease, and an increased incidence of thyroid disorders was found in the patients and their families. Mitochondrial antibodies which were present in twenty-six of the twenty-seven probands, were also found in one sister with liver disease and in 7% of healthy relatives, while none of the controls reacted in the test (<0·01). There was also a slight increase in nuclear and gastric parietal cell antibodies. Certain autoantibodies were strikingly clustered in some of the families. Serum immunoglobulins were measured in ninety-two relatives and showed a few instances of raised levels as well as some relatives with abnormally low values in the IgG, IgA and IgM classes. The findings suggest a familial or genetic abnormality of the immune responses as one of the predisposing factors in the development of primary biliary disease.