AChR-Seronegative Myasthenia Gravis Evaluation

Overview

  • EPIC Code:
  • IMO5538
  • Soft Test Code:
  • MUSKP
  • Send Out Test Code:
  • 1490
Alternate Names
  • MuSK and LRP4 Antibodies Panel
Included Tests

LRP4 Autoantibody Test; MuSK Antibody Test


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


Specimen Collection & Preparation

Specimen Requirements

2.0 mL Serum from a SST Gold Top Tube

Alternate Specimen

2.0 mL Serum from a Red Top Tube in a Plastic Vial

TransportAndStorage

72 hours Ambient
25 days Refrigerated (Transport)
25 days Frozen

Collection Instructions

Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form

Clinical Interpretation

Reference Range:

Refer to Interpretive Results


Methodology:
  • Immunofluorescence Assay (IFA), Radioimmunoassay

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


Documentation

Disease test for: Myasthenia Gravis (MG)


Production Schedule

Days Performed
Wednesday
Departments
  • Sendouts - Clinical
Turn Around Time

9 to 16 days


Coding & Compliance

CDM

00917080; 00918290


CPT Coding

86366, 86255