RNA Polymerase III Antibodies, IgG, Serum

Casandra

Casandra Test Code MC71797Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID RNAPCPT Code 83516

RNA Polymerase III Antibodies, IgG, Serum

Clinical Use

Use

RNA Polymerase III antibodies are useful for evaluating patients suspected of having systemic sclerosis, providing diagnostic and prognostic information about the disease. Systemic sclerosis (SSc) is characterized by vascular dysfunction, fibrotic changes in the skin and internal organs, and an autoimmune response. Antibodies against RNA polymerases are typically present in patients with SSc and are associated with diffuse cutaneous forms of the disease, leading to poor prognosis and increased risk for hypertensive kidney disease.

Special Instructions

Centrifuge and aliquot serum into a plastic vial for submission. The test is performed on Tuesdays and Thursdays, and requires a minimum specimen volume to yield a clinically relevant result on the first attempt. Specimens must be handled according to specified temperature stability guidelines to prevent rejection due to conditions such as gross hemolysis or lipemia.

Limitations

The test relies on an immunodominant epitope from RNA polymerase III, which does not cover all epitopes in the RNA polymerase I/III antigens. A negative result does not rule out the presence of antibodies targeting other epitopes. False positives can occur due to immune complexes or immunoglobulin aggregates. The presence of antibodies does not necessarily correlate with the severity of systemic sclerosis, although high titers may indicate a greater likelihood of disease.

Test Details

FDA Approved