C3 Glomerulopathy: A Review with Emphasis on Ultrastructural Features.

Area of Science:

• Nephrology
• Immunology
• Genetics

Background:

• C3 glomerulopathy (C3G) is a rare kidney disease characterized by dysregulation of the alternative complement pathway.
• It involves the deposition of complement component 3 (C3) in the kidney glomeruli.
• C3G includes dense deposit disease and C3 glomerulonephritis (C3GN).

Purpose of the Study:

• To summarize the understanding of C3 glomerulopathy (C3G) pathogenesis, clinical presentation, and diagnostic criteria.
• To highlight the role of alternative complement pathway dysregulation in C3G.
• To differentiate between C3G subgroups and other glomerular diseases.

Main Methods:

• Review of literature on C3 glomerulopathy (C3G) and complement pathway dysregulation.
• Analysis of diagnostic criteria including immunofluorescence and electron microscopy findings.
• Discussion of genetic and autoimmune factors contributing to C3G.

Main Results:

• C3G results from uncontrolled alternative complement pathway activation, leading to C3 deposition and membrane attack complex formation.
• Heterogeneous light microscopy findings often show a membranoproliferative pattern.
• Diagnostic confirmation relies on C3-dominant glomerular deposits on immunofluorescence and characteristic electron microscopy findings.

Conclusions:

• C3 glomerulopathy is driven by complement alternative pathway dysregulation, stemming from genetic or acquired factors.
• Accurate diagnosis requires specific immunofluorescence and electron microscopy patterns.
• Understanding the pathogenesis is crucial for differentiating C3G from other glomerular diseases.