Background Deficiency of the early components of the classical complement pathway (C1q, C1r, C1s, C4 and C2) is the strongest single genetic predisposing risk factor for the development of Systemic lupus erythematosus1. However data regarding complement deficiencies from developing countries is sparse, especially for pediatric onset systemic lupus erythematosus.
Objectives To assess complement levels C1q, C2, C3 and C4 in children with pediatric onset lupus during quiescent stage of disease.
Methods A cross sectional descriptive study was conducted between January and December 2012. 34 consecutive children with pediatric onset SLE (onset below 12 years), in quiescent stage (SLEDAI score zero) being followed at pediatric rheumatology clinic were enrolled. 29 age and sex matched healthy children were enrolled as controls. Clinical and immunological profile of patients was obtained from hospital records. C1q, C2, C3 were estimated by enzyme linked immunosorbent assay and C4 by end-point nephelometry. Genetic analysis was carried out in children with depressed levels of these complements.
Results Mean age at onset of lupus in study cohort was 9±2.1 yrs (range 1.5 – 12 years) and M: F ratio was 1:3. Mean duration of disease was 5.4 years (range 6 months – 11 years). ANA was positive in all, whereas anti dsDNA was positive in 19/34. Mean complement C1q, C2, C3 and C4 levels were 50.32, 17.28, 1320 and 236 mg/L respectively. Levels of complements were low in 7/34 children with SLE (features in table). Children with complement deficiency had distinct clinical and immunological profile. A very young age at onset and predominant skin manifestations were noted in C1q deficient children. Anti dsDNA titres were characteristically low in these patients and a speckled pattern was noted on ANA-IF. Mutation analysis revealed homozygous nonsense mutation in C1QA gene in two children with characteristic early onset disease at 1.5 and 2.5 years respectively.
Conclusions Clinical and immunological profiles were distinct among complement deficient lupus children, who had early and more severe disease. Inherited C1q deficiency (mutation in C1QA gene) was noted in two children in the cohort.
Manderson AP, Botto M, Walport MJ. The role of complement in the development of systemic lupus erythematosus. Annu Rev Immunol. 2004;22:431-56.
Acknowledgements This study was carried out as a MD Thesis, with support from the institute (PGIMER, Chandigarh, India).
Disclosure of Interest : None declared