ab1902

Juvenile idiopathic arthritis in multicase families

H.M. Säilä¹, H.A. Savolainen¹, K.M. Kotaniemi¹, O.A. Kaipiainen-Seppänen² M.T. Leirisalo-Repo³, K.V. Aho⁴

¹Rheumatism Foundation Hospital, Heinola; ²Department of Medicine, Kuopio University Hospital, Kuopio; ³Helsinki University Central Hospital, Department of Medicine, Division of Rheumatology, Helsinki; ⁴National Public Health Institute, Helsinki, Finland.

ABSTRACT
Objective
To characterize juvenile idiopathic arthritis (JIA) patients from multicase families.

Methods
The study series comprised 80 affected siblings belonging to 37 families. Comparisons were made with a population-based series of JIA patients from Finland and with a sibling series from the United States.

Results
The distribution of cases according to onset type was similar in the sibling and population-based series. The age at diagnosis was significantly lower in the sibling series (4.8 years vs 7.4 years; p < 0.001). There was more intra-pair similarity in onset and course types in the United States series compared to the Finnish series and the proportion of girls was higher in the former.

Conclusion
The only significant difference between familial and sporadic cases with JIA is an earlier onset of disease in familial cases. There is no essential difference in clinical features of the disease between patients in the multicase and sporadic groups. Differences between the Finnish and US series may be due to selection bias in the latter.

Key words
JIA, siblings, epidemiology.

Please address correspondence and reprint request to: Anneli Savolainen, Rheumatism Foundation Hospital, FIN-18120, Heinola, Finland.