Michels MAHM, Wijnsma KL, Kurvers RAJ, et al. - This study provides extensive description of clinical as well as laboratory results including complement features of an exclusively pediatric C3 glomerulopathy (C3G) cohort. Relatively benign outcome was evident, along with correlation of persistent low C3 with C3 nephritic factor (C3NeF) presence, and C3 glomerulonephritis (C3GN) was found to be related to higher soluble C5b-9 (sC5b-9) and lower properdin levels.

• Long-term follow-up was performed with extensive complement analysis of 29 Dutch children suffering from C3G [19 DDD(dense deposit disease), 10 C3GN].

• At presentation, lower estimated glomerular filtration rate (eGFR) was present in DDD patients.

• In 84% of all patients, there were low serum C3 levels at presentation.

• C3 levels continued to be low, during follow-up, in about 50% of patients all of which were C3NeF-positive.

• Relative to DDD patients, C3GN patients were found to have higher sC5b-9 and lower properdin levels.

• A median follow-up of 52 months showed an overall benign outcome.

• At last follow-up, eGFR was below 90 ml/min/1.73 m ² in only six patients.