Complement component C4 allotypes

Specimen:

5 mL blood in plain tube.

Serum should be frozen at -20°.

Method:

Immunoassay, gel based, genotyping.

Reference Interval:

Consult pathologist.

Application:

C4 allotyping is of limited use in the investigation of patients with autoimmune disease and persistent low or borderline C4 levels.

Interpretation:

Null alleles at the C4 loci are associated with a number of autoimmune diseases including SLE, Scleroderma and Rheumatoid arthritis.

Reference:

Ratnoff  W et al. Rheum Dis Clin North Am 1996; 22(1): 75-94.