PDF iconKidney Disease Testing Requisition Form (Effective beginning January 3, 2017)

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

C4 Nephritic Factors 
Dense Deposit Disease and C3 Glomerulonephritis 

Testing is appropriate for patients with C3 glomerulopathy (DDD and C3GN). C4 nephritic factor (C4Nef) is an autoantibody to the classical pathway C3 convertase (C4b2a). By stabilizing C4b2a, it prolongs the half-life of this convertase and protects C4b2a against decay dissociation by C4 binding protein (C4BP). C4Nef has been associated with several diseases including post-infectious glomerulonephritis (Halbwachs et al, 1980), systemic lupus erythematosus (Daha and van Es, 1980), membranoproliferative glomerulonephritis (Tanuma, et al. 1989) and meningococcal disease (Miller, et al. 2012).

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

MORL screening methodology 
MORL uses a hemolysis-based assay to detect the presence of C4Nef.

Turnaround time 
Turnaround time is ~4 weeks.

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

Cost & CPT Codes
See the MORL testing menu

References

Halbwachs L, et al.: Nephritic factor of the classical pathway of complement: immunoglobulin G autoantibody directed against the classical pathway C3 convertase enzyme. J Clin Invest. 1980, 65(6):1249-56. PMID: 6902727

Daha MR and van Es LA: Relative resistance of the F-42-stabilized classical pathway C3 convertase to inactivation by C4-binding protein. J Immunol. 1980, 125(5):2051-4. PMID: 6903579

Tanuma, Y, et al.: C3 nephritic factor and C4 nephritic factor in the serum of two patients with hypocomplementaemic membranoproliferative glomerulonephritis. Clin Exp Immunol. 1989, 76(1):82-5. PMID: 2736802

Miller, EC, et al.: Autoantibody stabilization of the classical pathway C3 convertase leading to C3 deficiency and Neisserial sepsis: C4 nephritic factor revisited. Clin Immunol. 2012, 145(3):241-50. PMID: 23117396