Benign monoclonal IgAK gammopathy associated with polyneuropathy and dysautonomia

The first case of benign IgAK monoclonal gammopathy associated with peripheral neuropathy is described. Dysautonomia is an unusual, yet prominent, manifestation of neuropathy in this patient. Electrodiagnostic testing and nerve biopsy were compatible with demyelination and axonal loss. Myelin sheath, perineural, and endoneural interstitial tissue fixation of anti-IgA and anti-kappa light chains was demonstrated by direct immunofluorescence microscopy. Absorption studies utilizing human peripheral nerve myelin resulted in complete removal of the paraprotein band. Analytic procedures with myelin-associated glycoprotein and gangliosides, however, were negative. Based on these findings, an alternative etiology for this neuropathy is hypothesized.