Complement component 3 (C3) is a critical protein in the immune system, forming a key part of the
complement cascade and innate immunity.

• C3 glomerulopathy describes kidney conditions where C3 deposits accumulate in the glomeruli
  without significant immunoglobulin presence, hinting at alternative complement pathway
  activation.
• Variants include Dense Deposit Disease (DDD) and C3 Glomerulonephritis (C3GN), sometimes
  linked to hereditary defects like CFHR5 nephropathy.
• Lupus nephritis involves kidney inflammation due to Systemic Lupus Erythematosus (SLE) and
  typically shows immunofluorescent positivity for IgG, IgA, IgM, C3, and C1q.