What is included in an Extractable Nuclear Antigen (ENA) panel?

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From the Guidelines

An Extractable Nuclear Antigen (ENA) panel typically includes tests for antibodies against chromatin, ribosomal P protein, spliceosome small nuclear ribonucleoproteins (Smith), Sjögren syndrome type A antigen (Ro), Sjögren syndrome type B antigen (La), and U1-ribonucleoprotein, as identified in the most recent expert panel proposal 1. The ENA panel is a crucial diagnostic tool for autoimmune disorders, particularly when antinuclear antibody (ANA) test results are positive.

  • The panel helps to detect specific autoantibodies associated with various autoimmune conditions, such as systemic lupus erythematosus (SLE), Sjögren's syndrome, and mixed connective tissue disease.
  • The most common targets of autoantibodies detected in SLE, as reported in the expert panel proposal, include chromatin, ribosomal P protein, and spliceosome small nuclear ribonucleoproteins (Smith) 1.
  • The presence of these antibodies indicates an immune response against the body's own nuclear components, which is a hallmark of autoimmune diseases.
  • The ENA panel is usually ordered as a follow-up test to a positive ANA result, providing more specific diagnostic information to guide treatment and management decisions.
  • It is essential to note that the ENA panel should be interpreted in the context of clinical presentation and other diagnostic findings, as discrepancies may arise between anti-ENA and ANA results or clinical presentation 1.

From the Research

Extractable Nuclear Antigen (ENA) Panel

An ENA panel is a test used to detect the presence of autoantibodies against specific extractable nuclear antigens. The following antigens are typically included in an ENA panel:

  • Jo-1 (histidyl-tRNA synthetase) 2
  • Scl-70 (topoisomerase) 2, 3
  • SS-A (Sjogren's syndrome A) 2, 3, 4, 5, 6
  • SS-B (Sjogren's syndrome B) 2, 3, 4, 5, 6
  • Sm (Smith) 2, 3, 4, 5, 6
  • Sm/RNP (Smith/Ribonucleoprotein) 2, 3, 4, 5
  • RNP (Ribonucleoprotein) 3, 4, 5

Detection Methods

Various methods can be used to detect anti-ENA antibodies, including:

  • ELISA (Enzyme-Linked Immunosorbent Assay) 2, 5
  • Counterimmunoelectrophoresis 4
  • Line immunoassay (LIA) 5
  • Fluorescence enzyme immunoassay (EliA) 5
  • Double dimension immunodiffusion 6

Clinical Significance

The presence of anti-ENA antibodies can be used to diagnose and monitor various autoimmune diseases, including:

  • Systemic Lupus Erythematosus (SLE) 2, 3, 4, 5
  • Sjogren's syndrome 2, 3, 5, 6
  • Scleroderma 2
  • Dermatomyositis 2
  • Polymyositis 2
  • Mixed Connective Tissue Disease (MCTD) 4
  • Autoimmune hepatitis (AIH) 6
  • Autoimmune sclerosing cholangitis (ASC) 6

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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