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MuSK and LRP4 Antibodies Panel
Test Code1490
CPT Codes
86366, 86255
Preferred Specimen
2 mL serum
Minimum Volume
0.5 mL
Instructions
Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form.
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
Room temperature: 72 hours
Refrigerated: 25 days
Frozen: 25 days
Refrigerated: 25 days
Frozen: 25 days
Methodology
Immunofluorescence Assay (IFA) • Radioimmunoassay (RIA)
Setup Schedule
Set up: as needed; Report available: 7-14 days
Clinical Significance
Detects anti-MuSK (muscle specific receptor tyrosine kinase) and anti-LRP4 (low density lipoprotein receptor-related protein 4) in the sera of patients with Myasthenia Gravis (MG). MuSK is a transmembrane endplate polypeptide involved in a signaling pathway that maintains the normal functional integrity of the neuromuscular junction (NMJ). The LRP4 protein activates MuSK kinase activity and promotes the clustering of the acetylcholine receptor (AChR) and its stabilization at the NMJ. Approximately 8% to 10% of all MG cases and 20% to 50% of the generalized MG cases who lack anti-AChR have anti-MuSK. Anti-LRP4 antibodies are detected in the serum of approximately 9.2% (range 2% to 50%) of MG patients who are negative for both anti-AChR and anti-MuSK.
