[Clinical characteristics of familial rheumatoid arthritis in Spain. A study of 73 families. Spanish Consortium for Rheumatoid Arthritis (CEAR) and European Consortium for Familial Rheumatoid Arthritis (ECRAF)].

OBJECTIVE

To describe clinical characteristics and the homogeneity of disease expression between involved members in multicase Spanish rheumatoid arthritis (RA) families.

PATIENTS AND METHODS

73 families with two or more siblings with RA were found, with a total of 149 patients distributed in 79 pairs (70 sib pairs, and 3 sib trios). Demographic, clinical and radiological characteristics were recorded in a standard questionnaire.

RESULTS

Clinical characteristics were similar to those of sporadic RA with a high frequency of women (78%), positive rheumatoid factor (RF) (86%), erosions (89%) and a 25% of the patients having extraarticular disease. The most important variable in disease severity was disease duration. The concordance between family members of the same age and calendar year of disease onset, and the pattern of disease expression, was not higher than expected, showing that the disease is heterogenic.

CONCLUSION

Environmental factors seem to be more important in RA susceptibility. Clinical characteristics of familiar RA in Spain do not seem to be different from sporadic RA, although differences were found in disease expression within families that may be due to variation of genetic or environmental factors, responsible for the susceptibility and disease duration.