Comparison of clinical and laboratory variables in familial versus sporadic systemic onset juvenile idiopathic arthritis.

OBJECTIVE: To compare patients with familial versus sporadic juvenile idiopathic arthritis (JIA) with respect to clinical and laboratory variables. METHODS: The familial JIA group comprised 11 affected siblings belonging to 4 families, while the comparative group comprised 22 patients selected by systematic sampling from JIA patients presenting to our pediatric rheumatology clinic; the first patient was chosen randomly and the subsequent patients chosen at intervals of 3. The 2 groups were compared with respect to demographic information, age at onset of disease, disease activity, disease damage, and laboratory variables. RESULTS: The 2 groups were comparable with respect to age, sex, and onset type of disease. All patients from the familial group were from a southern province of Saudi Arabia (p = 0.001). The familial group had an earlier age at onset of disease (p = 0.039), the mean number of actively inflamed joints was higher (p = 0.009), and functional capacity as measured by Childhood HAQ was worse (p = 0.048), compared with the sporadic group. Other variables showed no significant differences. CONCLUSION: The comparison of patients with familial versus sporadic JIA revealed a significant difference in origin of patients and age at onset of disease. These differences may be helpful in identifying the predisposing genes in familial patients with JIA.