THE FAMILIAL INCIDENCE OF RHEUMATOID SPONDYLITIS* BY

The familial incidence of rheumatoid spondylitis has not been adequately appreciated. The medical literature contains a few reports of families with more than one member having this form of spinal arthritis, but no serious effort to determine the familial incidence has been made. Two reports have described the existence of rheumatoid spondy-litis in brothers (Stecher and Hauser, 1946; Weil and Allolio, 1930) ; the occurrence in identical twins has also been noted (Campbell, 1947; Ray, 1932). Also Scott (1942) has mentioned the development of rheumatoid spondylitis in a brother and sister, in two sisters, and in a father and son. Dawson (1935) was convinced that the familial incidence of rheumatoid spondylitis was greater than the incidence in the general population, and referred to a report by Berckhardt of a family in which the patient's mother and four brothers also had rheumatoid spondylitis. On the other hand, in the excellent and comprehensive review of 1,035 cases of rheumatoid spondylitis (the largest recorded single series) reported by Polley and Slocumb (1947), the familial incidence of the disease was not discussed. The purpose of this paper is to report the familial incidence of rheumatoid spondylitis as it was found in a systematic study of the families of patients with rheumatoid spondylitis in the arthritis clini