In this study, 119 plasma biomarkers were identified to classify patients with PASC, among which an optimal set of nine proteins was determined, one of them significantly decreased (Frizzled related protein, FRZB) and eight of them significantly elevated (CXCL5, Adaptor-related protein complex 3 subunit sigma 2 (AP3S2), MYC-associated factor X (MAX), PDZ and LIM Domain 7 (PDLIM7), Ectodysplasin A Receptor (EDAR), Leukotriene A4 hydrolase (LTA4H), Calcium release activated channel regulator 2A (CRACR2A), and CXCL3). The gene discussed is MAX; the disease is long COVID-19.