Fibrillarin (U3 RNP) Antibody, IgG
Also known as: U3 FIB
Use
The presence of fibrillarin (U3-RNP) IgG antibodies in association with an ANA IFA nucleolar pattern is suggestive of systemic sclerosis (SSc). These antibodies in SSc are associated with distinct clinical features, such as younger age at disease onset and frequent internal organ involvement, including pulmonary hypertension, myositis, and renal disease. Fibrillarin antibodies are detected more frequently in African American patients with SSc compared to other ethnic groups. Strong correlation with ANA IFA results is recommended. In a multiethnic cohort of SSc patients, U3-RNP antibodies detected by immunoblot showed a high agreement with the immunoprecipitation assay.
Special Instructions
Not provided.
Limitations
The test's limitations include potential for missing some clinical cases if the specific ANA nucleolar pattern is not present or recognized. Approximately 71% of the borderline U3-RNP results with ANA nucleolar pattern in a multiethnic cohort were IP negative, indicating certain cases might not be identified. Discrepancies between ANA IFA patterns and U3-RNP detection should be considered in clinical correlation.
New York Approved
Methodology
Immunoassay (Immunoblot)
Biomarkers
Fibrillarin (U3-RNP) IgG
Protein
LOINC Codes
- 49963-2 - Fibrillarin Ab Ser Ql
Result Turnaround Time
1-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Serum separator tube
Storage Instructions
Refrigerated transport is recommended; frozen transport is also acceptable.
Causes for Rejection
Grossly hemolyzed or severely lipemic specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 2 weeks |
| Frozen | 1 month |
Other tests from different labs that may be relevant