C3c Fragment Level Assay

Dense Deposit Disease and C3 Glomerulonephritis 
Complement activation and inactivation generate the degradation products of complement component 3 (C3; MW: 195 kDa). C3 convertases (C4b2a generated by the classical or lectin pathways, or C3bBb generated by the alternative pathway) cleave C3 into C3a (MW: 9 kDa) and C3b (MW: 185 kDa). Factor I and its co-factors, including factor H, inactivate C3b forming iC3b (MW: 183 kDa) and C3f (MW: 2 kDa). iC3b is further degraded into C3c (MW: 140 kDa), C3d (MW: 35 kDa) and C3g (MW: 7 kDa). The plasma concentration of C3c is reflective of this activity.

The common pathophysiological basis of both Dense Deposit Disease (DDD) and C3 Glomerulonephritis (C3GN) is dysregulation of the AP complement cascade. Consumption of AP complement components is dependent on the degree of dysregulation of both the C3 and C5 convertases.  Plasma C3c levels are elevated in both DDD and C3GN as compared to controls (p<0.001).

Indications for screening 
Testing is appropriate for patients with DDD and C3GN.

MORL screening methodology 
Enzyme Linked Immuno-Sorbent Assay (ELISA)

Turnaround time 
Turnaround time is ~4 weeks.

Sample Required 
1 ml frozen EDTA plasma (see testing requisition for specimen handling).

Cost & CPT Codes

The Clinical Diagnostics Service of the Molecular Otolaryngology & Renal Research Laboratories is a CLIA-approved, Joint Commission-accredited diagnostic laboratory.