Child Kidney Dis.  2024 Oct;28(3):124-130. 10.3339/ckd.24.015.

C3 glomerulonephritis with genetically confirmed C3 deficiency in a pediatric patient: a case report

• Kim HM
• Shin JI
• Kim JH
• Oh J
• Kang JM
• Kang HG
• Kim SH
• Cho BS
• Lee KH

• KMID: 2560482
• DOI: http://doi.org/10.3339/ckd.24.015

Abstract

Complement component 3 glomerulonephritis (C3GN) is a rare kidney disease characterized by complement dysregulation that results in prominent complement component 3 (C3) deposition in the kidneys. The clinical course of C3GN varies from mild hematuria to progressive chronic kidney disease. In most patients, C3GN is driven by acquired factors, namely, autoantibodies that target C3 or C5 convertases. Genetic variations in complement-related genes are less frequent. We report the case of a 9-yearold Korean boy who presented with microscopic hematuria and a persistently low C3 level and had biopsy findings of C3GN, with the presence of a C3 gene mutation: a frameshift mutation associated with C3 deficiency. However, the patient did not exhibit any other symptoms of complement deficiency. Direct DNA sequencing of his family members revealed the same genetic mutation in his father and older brother. This case report is significant because there are very few such reports worldwide concerning gene mutations related to C3 deficiency to be discovered in patients with C3GN. Explaining C3GN pathogenesis is challenging; therefore, additional research is required in the future.

Keyword

Complement 3 Glomerulopathy; Complement Component 3 Deficiency; Case reports

Figure

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  Fig. 1. Clinical course of treatment to the patient. NGS, next-generation sequencing.

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  Fig. 2. Light microscopy, immunofluorescence, and electron microscopy findings. (A) Hematoxylin and eosin stain (×200). (B) Periodic Acid-Schiff stain (×400). The glomeruli are of moderately increased size and moderately hypercellular involving endocapillary cells. Mesangial interposition is occasionally seen, forming double contours. One glomerulus (8%) exhibits segmental sclerosis. Tubules reveal focal slight atrophy and loss with interstitial fibrosis. (C) Immunofluorescence (×200). Diffuse C3 deposits in the mesangium and glomerular capillary walls (IgG negative, IgM negative, IgA negative, C3+ diffuse granular peripheral and mesangial staining, C1q negative, C4 negative, fibrinogen 1+ diffuse granular peripheral staining, Kappa negative, Lamda negative). (D, E) Electron microscopy (×5,000). Heavy mesangial deposits and scattered big subepithelial “humps” as with localized subendothelial deposits. Mesangial interposition is rarely seen. Epithelial cell foot processes show focal marked effacement.

Reference

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