Non-genetic congenital and infantile nephrotic syndrome: New diagnostic and therapeutic management

Introduction About 30% of congenital and infantile nephrotic syndromes (CINS) are not caused by a genetic mutation. Non-genetic CINS (NGCINS) is a poorly characterized entity. No clear guidelines can be found in terms of diagnosis, prognosis and treatment of NGCINS patients. Noteworthy, NGCINS morbidity and mortality remain high, which makes it an important issue in Paediatric Nephrology. Material and methods This multicentric retrospective cohort study involved 12 paediatric nephrology departments across France. In total, 35 NGCINS patients, diagnosed between 1965 and 2015, were analyzed. Main outcomes included clinical presentation, pathology results, treatments used, relapses, survival, long-term renal function and morbidity. Results Thirty-five patients were analyzed. Six patients had no steroid treatment; 3 had spontaneous remission, 2 had persistent proteinuria evolving to ESRD and kidney transplantation; 1 had positive CMV PCR and was successfully treated with valganciclovir. Twenty-nine patients were treated with steroids; 13 were steroid-sensitive (SS), 16 patients were primary steroid-resistant (SR); 14 received one immunosuppressive therapy, 7 remained proteinuric, 2 of the latter died and 2 other evolved to ESRD and kidney transplantation. In sub-group analysis: pathology results were similar in SS and SR patients; morbidity (43% versus 0%), and mortality (3 patients versus 0) were higher in the SR group. Morbidity and mortality were higher in younger patients ( Conclusion This study attempts to characterize NGCINS. The following conclusions can be drawn: – CMV PCR should be proposed to every CINS patient; valganciclovir treatment should be used in case of a positive result; – 30-day oral steroid treatment should be initiated early, complementary methylprednisolone IV boluses do not seem efficient; – renal biopsy does not provide significant diagnostic or prognostic information; – genetic testing should be proposed early to CINS patients; – intensive immunosuppressive treatments should be initiated early for SR NGCINS patients; multiple lines of treatment can be used.