APOE and Alzheimer disease: MABs are currently being tested in cognitively unimpaired individuals at high risk, as there may be potential for preventative targeting of the large ‘preclinical AD’ population.5,6 However, MABs are costed at a high price and present risks such as amyloid related imaging abnormalities (ARIA) in individuals homozygous for the APOE ε4 allele.