C1q Nephropathy in Children with Nephrotic Syndrome: Treatment Strategies and Outcomes

INTRODUCTION: There is a paucity of clinical data on C1q nephropathy (C1qN) in children in India and Southeast Asia. This is the first detailed analysis conducted to elucidate the prevalence, clinicopathological profile, and response to different immunosuppressives in children with C1qN in India. MATERIALS AND METHODS: Detailed demographic profile, clinical features, urine and blood chemistries, kidney biopsy, and response to different immunosuppressives of the study participants were analyzed between August 2015 and October 2020 for steroid-dependent/-resistant nephrotic syndrome (NS). RESULTS: C1qN was diagnosed in 16 (14.13%) of 113 children who underwent biopsy for steroid-dependent/-resistant NS. The mean age was 44 months (range 18–99 months) and male and female number was 12 (75%) and four (25%), respectively, and mean follow-up was 3.5 years. Eight (50%) had coexistent minimal-change nephrotic syndrome (MCNS) pattern, seven (43.7%) had focal segmental glomerulosclerosis (FSGS), and one (6.2%) had diffuse mesangial hypercellularity. Thirteen children had complete follow-up, of which eight (61.5%) and four (30.7%) cases presented as steroid-dependent and primary steroid-resistant NS, respectively, whereas one (7.6%) had joint pain with rashes. At presentation, seven (53.8%) had hypertension, 12 (92.3%) had nephrotic range proteinuria, and six cases (46.1%) had hematuria. Nine (75%) of 12 cases achieved complete remission with calcineurin inhibitor (CNI) therapy, and two were non responders, one was a partial responder, and one responded to mycophenolate. Of six FSGS cases, four had complete remission, one had partial remission, and one was in non-remission. Of six cases with MCNS, five had complete remission and one was in non-remission. Renal functions remained normal in all except one case who had progression to chronic kidney disease Stage 3. CONCLUSION: One out of seven children with difficult NS can have underlying C1qN. CNIs are most beneficial to attain and maintain remission. Renal functions remain normal in the majority. Along with C1q deposits, MCNS and FSGS patterns are seen equally and respond almost similarly to CNIs.