14-3-3η (eta) Dx

Last updated: October 8, 2014

Synonyms:  IdentRA

CPT Codes:  86431, 86200, 83520

Description:  14-3-3η (eta) is a new test that may be useful in diagnosing patients with early undifferentiated polyarthritis or may be a marker for those who have a greater risk of developing rheumatoid arthritis (RA) or erosive arthritis.  14-3-3η is one isoform from a family of chaperone proteins involved in intracelluar and extracelluar signaling. 14-3-3η is not known to have a pathogenic role in RA but has been shown to induce numerous proinflammatory mediators.

Method:  Enzyme Linked Immunosorbent Immunoassay (ELISA) to detect the presence of the human protein, which is is 246 amino acids in length and has a molecular weight of 28.2 kDa.  Serum assays for 14-3-3η are commercially avaialable.   Antibody assays to detect anti-14-3-3η antibodies are not commercially available but have been positive in

Normal Values: Normal values are <0.2 ng/mL done by ELISA.  Values are not affected by age.

Increased in: Early or established rheumatoid arthritis or psoriatic arthritis patients with erosive disease. In one study nearly two-thirds of early RA patients were positive for 14-3-3η  and showed an overall sensitivity 77% and specificity of 93%.  Patients with elevated levels are more likely to have more severe disease with more radiographic damage or potential for radiographic progression. 14-3-3η levels do not correlate with acute phase reactant levels (ESR, CRP) or disease activity scores and weakly correlate with RF and CCP antibody levels.

Normal in: Negative/normal values would be expected in other rheumatic disorders like including psoriasis, osteoarthritis, gout, systemic lupus erythematosus, Sjögren’s syndrome, scleroderma, inflammatory bowel disease and fibromyalgia.

Indications: This assay may be useful (along with with rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibody testing)  in patients with early undifferentiated inflammatory arthralgias or arthritis. As 14-3-3η does not correlate with CRP or DAS-28 activty scores, it is unlikely to be useful as a serial biomarker in RA management.

Cost:   $50

BIBLIOGRAPHY
Maksymowych WP, van der Heijde D, Allaart CF, Landewé R, Boire G, Tak PP, Gui Y, Ghahary A, Kilani R, Marotta A.  14-3-3η is a novel mediator associated with the pathogenesis of rheumatoid arthritis and joint damage.  Arthritis Res Ther  2014;16:R99.  PMID: 24751211 

 


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