Imran Siddiqui, Joveria Farooqi, Farooq Ghani, Aysha Habib, Dilsha A Shariff.
Pattern of Anti-ENA (extractable nuclear antigens) antibodies in different clinical disorders; a clinical laboratory based study.
Int J Pathol Jan ;5(2):67-71.

Objective: To study the pattern of anti-Extractable Nuclear Antigen (ENA) antibodies in different autoimmune clinical disorders. Study Design: Retrospective laboratory-based descriptive study. Place and duration: The Aga Khan University Hospital (AKUH) Clinical Laboratories Karachi, Pakistan from Jan 1999 to Dec 2000. Patients and methods: Anti-ENA antibodies were ordered on 743 people from Aga Khan Clinical Laboratories. At the time of the test, 3ml clotted blood from each patient was analyzed for anti-Extractable Nuclear Antigen antibodies by the ELISA-based DISTAT ENA Profile kit (Shield Diagnostics). This data was retrospectively extracted from laboratory records of the last two years and from these, fifty in-patients of the AKUH diagnosed with various autoimmune clinical disorders were identified, their complete medical history recorded and the results analysed. Results: Out of 50 diagnosed cases of autoimmune disorders, 23 (46%) tested positive and 27 (54%) were negative for anti-ENA. Disorders associated with positive findings were: Mixed Connective Tissue Disease (9, 39%), Sjogren’s syndrome (5, 22%), Systemic Lupus Erythematosus (4, 17%), Scleroderma (3, 13%) and Rheumatoid Arthritis (2, 9%). Four patients, who were not diagnosed to have any specific autoimmune disorder, also showed positive results. The frequencies of antibodies against specific ENAs (anti-Ro/SS-A, anti-La/SS-B, anti-Sm, anti-RnP, anti-Scl-70) found in these disorders did not show any recognizable pattern of clinical association. Conclusion: The presence of auto-antibodies to ENA should not be taken as sole criterion for the final diagnosis of autoimmune clinical disorders. Anti-ENA profile must be considered in the light of clinical and laboratory findings before reaching definitive diagnosis.

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