This study is based on pedigrees of 192 patients with rheumatoid arthritis which are compared with pedigrees of 300 controls.
6,3 per cent of all relatives in the first group had rheumatoid arthritis compared to 0,38 per cent of all relatives in the control group. An hereditary predisposition to rheumatoid arthritis is definitevely to be admitted.
This predisposition is due to the presence of a principal autosomal dominant gene with reduced penetrance and variable expressivity. It seems to have no genetic relationship to the diathesis of allergic diseases and the diathesis of degenerative connective tissue disorders (mesenchymotic diathesis).