CHIT1 and early-onset autosomal dominant Alzheimer disease: Chitotriosidase 1 (CHIT1) is a human endochitinase that is believed to play a role in immune system response [90] and is increased in serum and CSF in various neurodegenerative diseases such as Alzheimer’s disease or ALS [91, 92] as a marker of neuroinflammation.