Rare Functional Variant in TM2D3 is Associated with Late-Onset Alzheimer's Disease

Area of Science:

• Genetics
• Neuroscience
• Molecular Biology

Background:

• Late-onset Alzheimer's disease (LOAD) is a complex neurodegenerative disorder with a significant genetic component.
• Previous research has identified various genetic risk factors, but the genetic architecture of LOAD remains incompletely understood.
• The CHARGE consortium and Icelandic AGES sub-study provide valuable resources for large-scale genetic association studies.

Purpose of the Study:

• To identify novel genetic variants associated with late-onset Alzheimer's disease (LOAD) risk.
• To investigate the functional impact of identified variants on TM2D3 gene function.
• To explore the potential role of TM2D3 in Alzheimer's disease pathogenesis.

Main Methods:

• Exome-wide association analysis (EWAS) was conducted in a large cohort of LOAD cases and controls.
• A specific rare variant (P155L) in the TM2D3 gene was identified and its enrichment in the Icelandic population noted.
• Functional studies using Drosophila models and human TM2D3 were performed to assess the variant's impact.

Main Results:

• A rare TM2D3 variant (P155L) was found to be significantly enriched in Icelandic individuals.
• This P155L variant was strongly associated with increased risk and earlier onset of LOAD in the Icelandic cohort.
• Functional assays confirmed that the P155L variant abolishes the protective function of TM2D3, identifying it as a damaging allele.

Conclusions:

• A rare TM2D3 variant (P155L) is a significant risk factor for late-onset Alzheimer's disease, particularly in the Icelandic population.
• The findings highlight the TM2D3 gene as a potential player in Alzheimer's disease susceptibility.
• This discovery may offer new insights into the molecular mechanisms underlying Alzheimer's disease, potentially involving the β-amyloid cascade.