Three families with polyneuropathy associated with monoclonal gammopathy.

OBJECTIVE To report familial occurrence of polyneuropathy associated with monoclonal gammopathy. DESIGN Case reports. PATIENTS We describe 6 patients (3 pairs) with a polyneuropathy associated with IgM monoclonal gammopathy. Four of the 6 patients had a demyelinating polyneuropathy on neurophysiological examination. Three patients had elevated antibodies against myelin-associated glycoprotein. No duplication on chromosome 17 or a mutation on chromosome 1 was found in any family. CONCLUSION Familial occurrence of polyneuropathy without the presence of hereditary motor and sensory neuropathy type I is a reason to search for the presence of monoclonal gammopathy.