What is the role of anti-lipoprotein-related protein 4 (LRP4) antibodies in the evaluation of myasthenia gravis (MG)?

Updated: Aug 27, 2018
  • Author: Abbas A Jowkar, MBBS; Chief Editor: Nicholas Lorenzo, MD, CPE, MHCM, FAAPL  more...
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Lipoprotein-related protein 4 is present on the postsynaptic membrane and is a coreceptor for agrin and is essential for for agrin-induced activation of MuSK in concert with Dok-7. Full activation of MuSK results in activation of rapsyn, which then induces clustering of  AChRs by binding them to the post-synaptic scaffold. Antibody to this protein is present in 9.2% of double seronegative myasthenics (absence of AChR and Anti-MuSK antobodies). However, 2 recent studies showed prevalence of anti-LRP4 antibodies varied from 2% to 50% of patients with double-seronegative MG from different geographic locations. [48, 49, 50]  LRP4 autoantibodies are predominantly IgG1, and studies suggest that they are pathogenic.

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