Functional validation of CHMP7 as an ADHD risk gene

Area of Science:

• Neurogenetics
• Developmental Neuroscience
• Pharmacology

Background:

• Attention deficit hyperactivity disorder (ADHD) is a childhood neurodevelopmental disorder with significant genetic underpinnings.
• Genome-wide association studies have identified CHMP7 as a potential risk gene for ADHD.
• A specific DNA variant (rs2294123) in CHMP7 is bioinformatically linked to reduced gene expression.

Purpose of the Study:

• To experimentally validate the role of CHMP7 in ADHD phenotypes.
• To create and characterize a zebrafish model for studying CHMP7's function in ADHD.
• To investigate the effects of methylphenidate on ADHD-related behaviors in the zebrafish model.

Main Methods:

• CRISPR-Cas9 genome editing was used to generate CHMP7-deficient zebrafish (chmp7+/-).
• Gene expression (mRNA levels) and brain volume were analyzed in chmp7+/- and wild-type (chmp7+/+) fish.
• Behavioral assays were conducted to assess hyperactivity in larval zebrafish.
• The efficacy of methylphenidate treatment was evaluated on observed hyperactivity.

Main Results:

• CHMP7 deficiency in zebrafish mirrored reduced mRNA levels seen in human ADHD risk allele carriers.
• CHMP7+/- zebrafish exhibited significant hyperactivity at 6 days post-fertilization, but not in later stages.
• A notable reduction in total brain volume was observed in chmp7+/- fish.
• Methylphenidate treatment effectively reduced hyperactivity in larval chmp7+/- zebrafish.

Conclusions:

• The study implicates CHMP7 as a crucial gene in ADHD neurodevelopment.
• The generated zebrafish model provides a valuable tool for functional studies of ADHD risk genes.
• CHMP7 plays a role in early neurodevelopmental processes relevant to ADHD phenotypes.