Comment: This patient was atypical for type 3 Alzheimer's disease in his late age of onset, but was in all other respects typical, including a cortical presentation with aphasia and dyscalculia, ApoE ε4-negative genotype, lack of family history (except in the tenth decade), neuropsychological testing suggesting an atypical presentation for Alzheimer's, with CSF indicative of Alzheimer's disease. Here, APOE is linked to Dyscalculia.