Novel PSEN1 G209A mutation in early-onset Alzheimer dementia supported by structural prediction

The Role of a Pathological Interaction between β-amyloid and Mitochondria in the Occurrence and Development of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases in existence. It is characterized by an impaired cognitive function that is due to a progressive loss of neurons in the brain. Extracellular β-amyloid (Aβ) plaques are the main pathological features of the disease. In addition to abnormal protein aggregation, increased mitochondrial fragmentation, altered expression of the genes involved in mitochondrial biogenesis, disruptions in the ER-mitochondria interaction, and mitophagy are observed. Reactive oxygen species are known to affect Aβ expression and aggregation. In turn, oligomeric and aggregated Aβ cause mitochondrial disorders. In this review, we summarize available knowledge about the pathological effects of Aβ on mitochondria and the potential molecular targets associated with proteinopathy and mitochondrial dysfunction for the pharmacological treatment of Alzheimer's disease.

Novel PSEN1 p.Gly417Ala mutation in a Korean patient with early-onset Alzheimer's disease with parkinsonism

Mutations in presenilin 1 (PSEN1) are the most common cause of autosomal dominant Alzheimer's disease. Here, we report a 37-year-old male Korean patient carrying a PSEN1 p.Gly417Ala mutation with exceptionally early and severe presentations, including a wide range of atypical symptoms of rapid cognitive decline with a stooped posture, rigidity, and bradykinesia. Targeted next-generation sequencing of proband revealed a novel nucleotide substitution (c.1250G>C) in exon 12 of PSEN1 gene, altering glycine to alanine at 417 position. Three-dimensional protein structure prediction revealed that the variant may cause perturbations in the 8th transmembrane region, perturbing its functions from the increased hydrophobicity and size of alanine with decreased flexibility. Since several glycine>alanine substitutions in other PSEN1 transmembrane helices revealed aggressive Alzheimer's disease phenotypes, PSEN1 Gly417Ala may share a common pathogenic mechanism.

Mutations, associated with early-onset Alzheimer's disease, discovered in Asian countries

Alzheimer's disease (AD), the most common form of senile dementia, is a genetically complex disorder. In most Asian countries, the population and the number of AD patients are growing rapidly, and the genetics of AD has been extensively studied, except in Japan. However, recent studies have been started to investigate the genes and mutations associated with AD in Korea, the People's Republic of China, and Malaysia. This review describes all of the known mutations in three early-onset AD (EOAD) causative genes (APP, PSEN1, and PSEN2) that were discovered in Asian countries. Most of the EOAD-associated mutations have been detected in PSEN1, and several novel PSEN1 mutations were recently identified in patients from various parts of the world, including Asia. Until 2014, no PSEN2 mutations were found in Asian patients; however, emerging studies from Korea and the People's Republic of China discovered probably pathogenic PSEN2 mutations. Since several novel mutations were discovered in these three genes, we also discuss the predictions on their pathogenic nature. This review briefly summarizes genome-wide association studies of late-onset AD and the genes that might be associated with AD in Asian countries. Standard sequencing is a widely used method, but it has limitations in terms of time, cost, and efficacy. Next-generation sequencing strategies could facilitate genetic analysis and association studies. Genetic testing is important for the accurate diagnosis and for understanding disease-associated pathways and might also improve disease therapy and prevention.