Alzheimer’s disease (AD), one of the most prevalent neurodegenerative diseases, is characterized by the deposition of amyloid-beta (Aβ) peptides and the presence of neurofibrillary tangles composed of hyperphosphorylated Tau protein. While inherited forms of AD—termed familial AD—only account for 3–5% of AD cases, the prevalence of familial AD is comparable to that of other neurological disorders such as Huntington’s disease and amyotrophic lateral sclerosis (ALS). Familial AD is caused by mutations or gene copy number variation in the genes that encode APP (amyloid precursor protein), presenilin 1, and presenilin 2, resulting in excessive production of Aβ. Despite considerable advances in our understanding of the genetic causes of familial AD, there is currently no effective disease-mo...[ Read more ]

Alzheimer’s disease (AD), one of the most prevalent neurodegenerative diseases, is characterized by the deposition of amyloid-beta (Aβ) peptides and the presence of neurofibrillary tangles composed of hyperphosphorylated Tau protein. While inherited forms of AD—termed familial AD—only account for 3–5% of AD cases, the prevalence of familial AD is comparable to that of other neurological disorders such as Huntington’s disease and amyotrophic lateral sclerosis (ALS). Familial AD is caused by mutations or gene copy number variation in the genes that encode APP (amyloid precursor protein), presenilin 1, and presenilin 2, resulting in excessive production of Aβ. Despite considerable advances in our understanding of the genetic causes of familial AD, there is currently no effective disease-modifying therapy. Notably, CRISPR/Cas9-mediated genome editing could precisely modify the genetic variants, which could be a potential disease-modifying treatment strategy for familial AD. However, development of a CIRSPR/Cas9-mediated therapy for familial AD therapy faces several obstacles. In particular, specific targeting approaches are required for different types of disease-causing variants. Efficient delivery of the genome-editing system into the brain are also needed for the therapeutic development. In this thesis, I first describe my work on the development of an efficient footprint-free manipulation of gene dosage in human induced pluripotent stem cells (iPSCs) using CRISPR/Cas9 nickases. And I demonstrated that correction of APP copy numbers in iPSC line carrying 3 copies of APP reduces disease-associated phenotypes of Aβ production and tau hyperphosphorylation. I also developed a brain-wide genome editing system and demonstrated allele specific disruption of a familial AD mutation throughout the brain alleviates Aβ-associated pathology and improves cognitive functions in the mice. The development of brain-wide genome editing system can be further applied to other brain disorders that affecting multiple brain regions. These works provide new therapeutic targets as well as novel therapeutic strategies for AD treatment.