Theme 4 In vivo experimental models.

Area of Science:

• Neuroscience
• Genetics
• Animal Models

Background:

• Amyotrophic Lateral Sclerosis (ALS) is often sporadic (90%) with familial cases (10%).
• Next-generation sequencing increases analyzed genes, complicating variant interpretation.
• Functional analyses are crucial for determining variant pathogenicity.

Purpose of the Study:

• To develop a simple Zebrafish model for functional analysis of candidate ALS-associated genetic variants.
• To assist in the interpretation of genetic variants identified in routine diagnostics.

Main Methods:

• Transient overexpression of ALS-associated genetic variants via mRNA injection in Zebrafish embryos.
• Assessment of embryonic mortality, developmental delays, and morphological abnormalities.
• Analysis of axonal length, axonal branching, and motor performance in Zebrafish larvae.

Main Results:

• The Zebrafish model successfully validated known ALS mutations (SOD1-Gly93Ala, OPTN Glu478Gly), showing expected axonal and motor deficits.
• Overexpression of candidate variants SOD1 p.Glu134del and OPTN p.Leu492Arg induced morphological abnormalities and motor impairments.
• WT SOD1 overexpression did not produce these adverse effects, confirming variant-specific impacts.

Conclusions:

• A Zebrafish model was established for functional variant pathogenicity analysis in ALS, aiding molecular diagnostics.
• The model demonstrated utility in assessing the pathogenicity of SOD1 and OPTN variants.
• This approach enhances the interpretation of genetic testing results for ALS patients.