For instance, the increases in MAO-B activity that appear to align much more strongly with carriers of the APOE ε4 allele is novel and given the implied role of MAO-B in neurodegeneration and the gender-risk of AD associated with the APOE ε4 allele, it is not unreasonable to infer that their contributions to AD reflect an overlapping mechanism. Here, APOE is linked to Alzheimer disease.