Impact of C1q deficiency on the severity and outcome of childhood systemic lupus erythematosus

Objective: To delineate the clinical and laboratory features of systemic lupus erythematosus (SLE) in C1q‐deficient Saudi children and to compare them with sporadic SLE patients with respect to their clinical and laboratory features and disease outcome. Methods: The C1q‐deficient SLE patient group comprised 14 patients, while the comparative group comprised 11 patients selected by systemic sampling from our pediatric lupus clinic database. The two groups were compared with respect to: demographic, clinical and laboratory variables and outcome. Results: The C1q‐deficient SLE patients had an earlier age of onset of disease (P = 0.003); 43% had familial SLE and none of the comparative group had family histories of SLE. The two groups were comparable with respect to gender, disease duration and follow‐up. Scarring alopecia, discoid rash and nail changes were more frequent in the C1q‐deficient SLE patient group. However, there were no significant differences. The mean white blood cell count was lower (P = 0.04) and the level of anti‐Sm and anti‐phospholipid antibodies were higher (P = 0.04) in the C1q‐deficient SLE patients. Other variables did not show significant differences. Two patients from the C1q‐deficient SLE patient group died due to infection. All patients from the control group are alive. Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index mean was higher in the C1q‐deficient SLE patients group but was not statistically significant. Conclusion: C1q‐deficient SLE patients tend to be younger and more likely to have familial disease with severe cutaneous manifestations. The mortality among them is more frequent, which may reflect disease severity.