Serological abnormalities in families of patients with rheumatoid arthritis: eight to twelve years follow-up study.

Serum gammaglobulin level, the presence of rheumatoid factor and of anti-nuclear antibodies were re-examined after 8 to 12 years in families of 21 seropositive rheumatoid arthritis patients. In the time 8 members of the families developed rheumatoid arthritis and the number of persons with elevated serum gammaglobulins increased. Rheumatoid tests yielded variable results. No relationship could be demonstrated between development of disease symptoms and the earlier presence of rheumatoid factor.