To examine the functional relevance of CHMP7 to ADHD, we generated a chmp7 zebrafish mutant line using CRISPR-Cas9 genome editing, and hypothesised that chmp7 heterozygous (chmp7+/−) animals would mimic the reduction in transcripts correlated with the ADHD-associated SNP (rs22941239). This evidence concerns the gene CHMP7 and attention deficit-hyperactivity disorder.