A 9-gene combination, (FGD3, CENPI, AURKB, DEPDC1B, FAM83D, NCAPH, TNFRSF18, FCGR1A, DEPDC1), has been identified, whose expression pattern can distinguish the PD group from the MD and WD groups with 96.3% classification accuracy (94.5% sensitivity and 97.3% specificity). This evidence concerns the gene TNFRSF18 and Wilson disease.