Update on ADHD genetics: A practitioner's perspective: Mise à jour sur la génétique du TDAH : le point de vue d'un praticien.

Abstract

BackgroundAttention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterized by early-onset inattention, hyperactivity, and impulsiveness. Affecting 5% to 10% of youth and persisting into adulthood in &#x223c;6%, ADHD is frequently discussed in genetic terms by patients and their families, making it essential for clinicians to understand current genetic evidence.ObjectiveTo summarize contemporary genetic findings relevant to ADHD across the lifespan and provide practical guidance for clinicians on assessment, treatment, and psychoeducation.Scope and methodsThis focused narrative review integrates evidence from family and twin studies, genome-wide association studies (GWAS), copy number variants (CNVs), polygenic risk scores (PRS), and Mendelian randomization (MR), as well as pharmacogenetics and studies of gene-environment interplay.FindingsADHD is highly heritable (&#x223c;70%), comparable to other major neuropsychiatric conditions. GWAS reveals that thousands of common variants collectively contribute to risk (i.e., polygenic), though each has a small effect. Rare CNVs are more frequent in ADHD than controls and overlap with CNVs in autism. Genetic findings implicate neurodevelopmental pathways expressed in early brain and frontal cortical circuits. ADHD genetic risk correlates with cognitive traits, risk-taking behaviours, and multiple psychiatric and physical health outcomes. Gene-environment correlations and interactions influence risk and course. Pharmacogenetic evidence supports <i>CYP2D6</i> genotyping for atomoxetine dosing; routine genetic testing for stimulant selection is not justified.Clinical implicationsThere are no diagnostic genetic tests for ADHD. Assessment should prioritize functional impairment, developmental and family history, and comorbidity. Psychoeducation should emphasize modifiable risks and the interplay of genes and the environment. While genetic insights may eventually refine diagnosis and personalized care, current best practice relies on comprehensive clinical evaluation and multimodal management.ConclusionGenetic research confirms ADHD's neurodevelopmental basis, continuity across the lifespan, and overlap with other neurodevelopmental conditions of childhood. Clinicians can use these insights for counselling and risk monitoring while avoiding over-reliance on genetic testing outside targeted pharmacogenetic use. <b>Update on ADHD Genetics: A Practitioner&#x2019;s Perspective</b>Attention deficit/hyperactivity disorder (ADHD) is a common condition that usually begins in childhood and can continue into adulthood. It affects attention, activity level, and impulse control. About 5&#x2013;10% of children are diagnosed with ADHD, and for some people, symptoms continue later in life. Because ADHD often appears in more than one family member, many people wonder how much genetics plays a role.Research shows that genes do influence ADHD, but there is no single &#x201c;ADHD gene.&#x201d; Instead, many genes each contribute a very small amount to a person&#x2019;s likelihood of developing ADHD. These genetic influences affect early brain development, supporting the idea that ADHD is a brain based condition. Some of the same genetic factors are also involved in other neurodevelopmental conditions, such as autism. Genetic risk linked to ADHD is also related to traits like attention, activity level, and risk taking, as well as some mental and physical health conditions.Genes do not act alone. Environmental factors such as school demands, family environment, and life stress also play an important role in how ADHD develops and how much it affects daily life. Genetics can help explain why some people are more vulnerable than others, but it does not explain why ADHD diagnosis rates change over time or differ between communities.There is currently no genetic test that can diagnose ADHD or determine which ADHD medication will work best for an individual. Diagnosis is made through clinical evaluation that focuses on symptoms, daily functioning, development, and family history. Genetic information can be helpful for understanding ADHD and discussing it with families, but care and treatment are still guided by careful assessment and personalized support, not by genetic testing.