Figure 1.

(A) CHIT1, (B) CHIT1 activity, (C) CHI3L1, (D) CHI3L2 by baseline age. Dashed line indicates linear regression including all data. CSF, cerebrospinal fluid; CHIT1, Chitotriosidase 1; CHI3L1, Chitinase 3‐like protein 1; CHI3L2, Chitinase 3‐like protein 2; HC, healthy control; At‐risk, presymptomatic gene carrier; C9ORF72, C9ORF72 hexanucleotide repeat expansion carrier; A4V, SOD1 A4V mutation carrier; non‐A4V, SOD1 non‐A4V mutation carrier; none, no mutation; Other, carrier of other highly penetrant ALS‐causing gene mutation.