Evaluation of the Diagnostic Utility of Caveolae-associated Protein 4 (cavin-4) Epitope-based ELISA in Identification of Immune Mediated Rippling Muscle Disease
Reghann LaFrance-Corey1, Haidara Kherbek1, Margherita Milone1, Pranjal Gupta2, Gregory J. Kraus1, Teerin Liewluck1, William Litchy1, Sean Pittock1, John Mills1, Andrew Knight1, Divyanshu Dubey1
1Neurology, Mayo Clinic, 2Wayne State University

To evaluate utility of caveolae-associated protein 4 (cavin-4) peptide enzyme-linked immunosorbent assay (ELISA) for detection of cavin-4 IgG among patients with immune-mediated rippling muscle disease (iRMD).


iRMD is an autoimmune muscle disease associated with wave-like muscle rippling and percussion-/stretch-induced muscle mounding. Cavin-4-IgG is a novel autoantibody biomarker of iRMD discovered utilizing phage immunoprecipitation sequencing (PhIP-Seq). Peptide-based ELISA offers a high-throughput method to detect patient IgG targeting varying epitopes of cavin-4 in iRMD patients.


Sera from iRMD patients evaluated at Mayo Clinic were tested on whole-human proteome PhIP-Seq to identify cavin-4 epitopes. Peptide-based ELISA and cavin-4-transfected HEK293 cell-based assay (CBA) were utilized for autoantigen confirmation.  


Nine patients (5 males) with archived sera within 1 year of iRMD diagnosis were identified (median age 53 [range 19-77] years). PhIP-Seq data revealed cavin-4 as the candidate autoantigen in all patients. Cavin-4 peptide 288-337 amino acid had one of the highest enrichment scores on whole human proteome PhIP-Seq in the majority of patients evaluated (56%). All nine patients were positive by cavin-4 288-337 amino acid peptide ELISA, while only seven of the nine patients were positive on cavin-4 CBA. Archived sera from healthy (CBA n=66, ELISA n=76) and disease controls (ELISA: hyper-gamma globulinemia [HGG], n=9; systemic lupus erythematosus, n=10; multiple sclerosis [MS], n=8; anti-mitochondrial antibody [AMA], n=12 and CBA: HGG, n=7; MS, n=8; AMA, n=12) tested uniformly negative. Clinical presentation of cavin-4 IgG seropositive patients included rippling of lower limb muscles (n=9), proximal weakness (n=4), and myalgia (n=9). All patients had percussion-induced muscle rippling and half had percussion- or stretch-induced muscle mounding. Only one of nine patients had underlying malignancy.


Cavin-4-IgG is a novel biomarker associated with immune-mediated rippling muscle disease. Our study highlights that cavin-4 epitope-based ELISA improves sensitivity without sacrificing specificity for cavin-4 IgG detection in iRMD.