Hereditary abnormalities have a role in the development of Alzheimer's disease. Pathological hallmarks of the Alzheimer's disease family of neurodegenerative disorders include tau protein accumulation in brain tissue, heterochromatin decondensation, piwi and piRNA loss, and resulting transposable element dysregulation . The cytoskeleton is disrupted by hyperphosphorylated Tau, which causes synaptic dysfunction and cell death . Global chromatin relaxation is one mechanism by which tau promotes neurodegeneration; loss of heterochromatin is common in Alzheimer's disease in humans; and aberrant gene expression results from loss of heterochromatin in tauopathies . There are presently 21 recognised chromosomes that are associated with Alzheimer's disease, 19 with APOE, 17 with Tau, 14 with PS-1, and 1 with PS-2 . An aberrant gene on chromosome 1, for instance, has the potential to cause over 350 disorders, such as cancer, mental retardation, Alzheimer's disease, and Parkinson's disease .