LRP4 and myasthenia gravis: Autoantibodies to low density lipoprotein 4 (LRP4), agrin, and ColQ have been described in association with MG, however, their specificity remains to be determined, pathogenic mechanisms have not been fully elucidated, and there has been no animal models showing disease in response to passive transfer of antibodies which is an essential criterion in determining whether antibodies are truly pathogenic (32).