Clinical and laboratory features of anti-MAG neuropathy without monoclonal gammopathy

Elba Pascual-Goñi,Jordi Díaz-Manera,Laura Martínez-Martínez,Cándido Juárez,Esther Moga,Luis Querol,Ricard Rojas-García,Manuel J Simón-Talero,Elena Cortés-Vicente,Lorena Martín-Aguilar,Isabel Illa,Cinta Lleixà

doi:10.1038/s41598-019-42545-8

Abstract

Antibodies against myelin-associated glycoprotein (MAG) almost invariably appear in the context of an IgM monoclonal gammopathy associated neuropathy. Very few cases of anti-MAG neuropathy lacking IgM-monoclonal gammopathy have been reported. We investigated the presence of anti-MAG antibodies in 69 patients fulfilling diagnostic criteria for CIDP. Anti-MAG antibodies were tested by ELISA and confirmed by immunohistochemistry. We identified four (5.8%) anti-MAG positive patients without detectable IgM-monoclonal gammopathy. In two of them, IgM-monoclonal gammopathy was detected at 3 and 4-year follow-up coinciding with an increase in anti-MAG antibodies titers. In conclusion, anti-MAG antibody testing should be considered in chronic demyelinating neuropathies, even if IgM-monoclonal gammopathy is not detectable.

Highlights

Antibodies against myelin-associated glycoprotein (MAG) almost invariably appear in the context of an IgM monoclonal gammopathy associated neuropathy
Anti-MAG antibodies were detected in four patients (6.9% of the seronegative patients; 5.8% of the whole chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) cohort) without IgM monoclonal gammopathy
We identified anti-MAG antibodies in four patients fulfilling CIDP diagnostic criteria and no evidence of monoclonal gammopathy

Summary

Introduction

Antibodies against myelin-associated glycoprotein (MAG) almost invariably appear in the context of an IgM monoclonal gammopathy associated neuropathy. Anti-MAG antibody testing should be considered in chronic demyelinating neuropathies, even if IgM-monoclonal gammopathy is not detectable. Anecdotal cases of neuropathy with anti-MAG antibodies lacking monoclonal gammopathy were reported[6,7,8]. A recent Japanese study[8] reported a prevalence of 5.6% of anti-MAG positive patients in a cohort of 36 patients with chronic demyelinating polyneuropathy with no monoclonal gammopathy. Antibodies in these patients were tested by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot analysis. We investigate the presence of anti-MAG antibodies in patients fulfilling diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) without IgM monoclonal gammopathy. We describe the clinical, electrophysiological and laboratory findings of four patients with anti-MAG associated neuropathy without any detectable monoclonal gammopathy at the time of diagnosis

Methods

Results

Conclusion