Supplementary Material for: Contactin-1 Associated Membranous Nephropathy after multiple mRNA 1273 COVID-19 Vaccinations: A Case Report

Contactin-1 associated membranous nephropathy is a rare type of membranous nephropathy
typically seen in the setting of chronic inflammatory demyelinating polyneuropathy (CIDP). Here
we present a case of a 79-year-old man who presented with ankle edema and was found to have
2,888 milligrams of proteinuria per 24 hours and membranous nephropathy on kidney biopsy.
Staining for multiple membranous antigens including phospholipase A-2 receptor, NELL-1, and
EXT-2 were negative. Liquid chromatography tandem mass spectrometry was performed on
glomeruli and identified Contactin-1 as the target antigen. Classic secondary causes of
membranous nephropathy were excluded including systemic autoimmune disease, malignancies,
and medications. Interestingly, the membranous nephropathy occurred one month after receiving
five doses of mRNA Covid 1273 vaccinations that occurred over a 19-month period. The patient
subsequently underwent spontaneous remission without initiation of disease targeted therapy
suggesting a tentative association between the Covid-19 vaccination and the membranous
nephropathy. Additionally, this patient did not have any significant neuropathies typically seen
with Contactin-1 associated membranous nephropathy. To our knowledge, this is the first case
report demonstrating a temporal association between Contactin-1 associated membranous
nephropathy and vaccination against Covid-19 with mRNA 1273. Our findings in this case
broaden the clinical spectrum of the rare Contactin-1 associated membranous nephropathy.