<qa>  What is the name of the protein that attacks the myelin sheath of nerveThis study will test the safety and effectiveness of the drug Rituximab in treating a nerve disease called MGUS also known as neuropathy with anti-MAG antibodies. Patients with MGUS have an abnormal protein called monoclonal IgM immunoglobulin that attacks the myelin sheath protective coating of nerves, causing them to not function properly. The disease affects the nerves in the legs or arms, and patients have numbness, tingling, muscle weakness, and unsteady gait. There are no adequate treatments. Immunosuppressive drugs or human immunoglobulin infusions can produce mild and transient improvement, but the benefits of these therapies are not significant. 