To gauge if CHI3L1 could be a monitoring biomarker candidate for APBD as well, we measured brain Chi3l1 mRNA and protein levels in Gbe1YS and found them significantly increased (Fig. 5D,E), raising the possibility that YKL40 could be used as a tool to track the progression of neuroinflammation in PB diseases. Here, CHI3L1 is linked to adult polyglucosan body disease.