CHI3L1 and bipolar disorder: Ch3L1 (in humans also named YKL-40) can be assumed as an almost universal marker of diseases: for neural pathologies, it has been suggested as a biomarker of multiple sclerosis (31), traumatic brain injury (32), Alzheimer's disease (33), amyotrophic lateral sclerosis (34), iatrogenic and sporadic Creutzfeldt-Jakob disease (35), or bipolar disorder (36)—not to mention various pathologies in peripheral organs.