Gene

Genome-wide association study

Psychiatry

Genotype

Genetic linkage

Missing heritability problem

Single-nucleotide polymorphism

Psychology

Heritability

Twin study

Genetic association

Comorbidity

Attention deficit hyperactivity disorder

Genetic variants

Genetics

Candidate gene

Biology

Molecular Psychiatry

Decades of research show that genes play an vital role in the etiology of attention deficit hyperactivity disorder (ADHD) and its comorbidity with other disorders. Family, twin, and adoption studies show that ADHD runs in families. ADHD's high heritability of 74% motivated the search for ADHD susceptibility genes. Genetic linkage studies show that the effects of DNA risk variants on ADHD must, individually, be very small. Genome-wide association studies (GWAS) have implicated several genetic loci at the genome-wide level of statistical significance. These studies also show that about a third of ADHD's heritability is due to a polygenic component comprising many common variants each having small effects. From studies of copy number variants we have also learned that the rare insertions or deletions account for part of ADHD's heritability. These findings have implicated new biological pathways that may eventually have implications for treatment development.

Genetics of attention deficit hyperactivity disorder