]> 2026-07-31T11:52:05+00:00 WBR0313 0 en Presenilin Mutations in the genes encoding presenilin 1 (chromosome 14) and presenilin 2 (chromosome 1) proteins cause early-onset forms of familial Alzheimer’s disease. However, presinilin mutations are not associated with Down syndrome. Apolipoprotein E The E4 variant of apolipoprotein E (chromosome 19) is a susceptibility factor that is associated with late-onset sporadic Alzheimer’s disease. Individuals who carry two ''APOE4'' alleles have a 20-fold increased risk of Alzheimer’s disease compared with non-carriers. ''APOE'' allele status is not specifically related to Down syndrome. α-synuclein Tau Hyperphosphorylated tau composes the pathological neurofibrillary tangles which affects the brains of patients with Alzheimer’s disease. Although tau proteins are involved in the pathogenesis of the disease, they are not thought to be associated with the accelerated development of Alzheimer’s disease associated with Down Syndrome. Amyloid precursor protein An extra copy of the amyloid precursor protien (APP) on chromosome 21 is associated with the accelerated development of Alzheimer’s disease among patients with Down syndrome. Genetics A 40-year-old man with Down syndrome is brought to his primary care physician by an employee of his assisted care facility for memory loss. The employee explains that the patient has always had baseline intellectual disability, but his condition has significantly worsened over the past year. He has increasingly forgotten where his room is and is unable to recognize staff he used to know well. Which of the following proteins is most likely responsible for predisposing the patient to his symptoms? E Neurology 2020-10-28T00:09:47Z 2459150.506794 WBR0313