BACE1 and early-onset autosomal dominant Alzheimer disease: Then, the enzyme that mediated CHL1 function was suggested to play a role in axon guidance as well: the integrated function of BACE1 (the β-secretase enzyme that initiates production of the β-amyloid peptide involved in Alzheimer disease) was necessary for CHL1 to exert the function in axon guidance in the hippocampus [54].