SEZ6L2 and COVID-19: Upregulated serum proteins at day 2 were associated with neuronal activity [Adam23 (50), Sez6L2 (51), Gfra1 (49), Igsf3 (53), Matn2 (46)], lysosomal protein degradation [TPP1, tripeptidyl peptidase 1 (55)], and COVID-19 myocardial injury [Matn2 (56)] and disease severity [Tnfsf12 (57), CXCL1 (58)].