The Extractable Nuclear Antibodies (ENA) assay detects the presence of autoantibodies in the blood that react with proteins in the cell nucleus. This test is primarily used to confirm the presence of specific antibodies as follow-up after a positive ANA IFA test (specifically with speckled pattern). This test collectively screens for the extractable nuclear antibodies. If the screen is positive, the following individual antibodies will be tested and reported: dsDNA, Chromatin, Ribosomal P, SSA/Ro, SSB/La, Centromere B, Sm, SmRNP, RNP, Scl-70 and JO1.
See the Mixed Connective Tissue Disease Panel Algorithm for further information on suggested ordering of this test.
SSA/SSB: Positive result supports the diagnosis of Sjogren's syndrome or other connective tissue diseases.
Sm: Positive result supports diagnosis of SLE with renal involvement
RNP: Positive result supports diagnosis of mixed connective tissue disease, which resembles SLE but is not accompanied by renal involvement.
Scl-70: Positive result supports diagnosis of scleroderma
Jo-1: Positive result supports diagnosis of polymyositis