AICDA and membranous glomerulonephritis: Indeed, in some patients with IgG4-AID, class switch has been observed: In CNTN1 antibody-associated neuropathy and membranous nephropathy with PLA2R antibodies or acute autoimmune paranodopathy, a class switch from complement-fixing IgG1 or IgG3 in the acute disease phase towards IgG4 in the chronic phase has been observed (115–118).