Using the 12 most differentially abundant proteins (CHI3L1, TMEM198, CHIT1, CHI3L2, HYOU1, XXYLT1, DPP6, C1QB, FABP5, MERTK, UCHL1, and WARS), PCA effectively distinguished ALS from controls (Fig. 7a). This evidence concerns the gene XXYLT1 and amyotrophic lateral sclerosis.