Notes

Antibody results should not be used alone for diagnosis and must be interpreted in light of clinical manifestations and other test results.
U1RNP antibodies typically appear in both SLE and mixed connective tissue disease (MCTD, Sharp Syndrome). In MCTD, the presence of U1RNP antibodies is required for diagnosis, whereas they occur in only 30 to 40% of SLE patients. Several studies have shown that an anti-U1RNP response in the absence of RNP70 antibodies is strongly associated with SLE.