[Genetics of ADHD in clinical practice]

Attention-deficit/hyperactivity disorder (ADHD) is a complex and heterogeneous neurodevelopmental disorder from a causal, clinical and prognostic perspective. Research reflects its multifactorial nature with a prominent role of genetic factors. Population studies have historically pointed to the involvement of numerous genetic variants of small effect size, which hardly by themselves increase the risk of presenting the disorder and hardly justify its high heritability. Many of them are present in more than 60% of the general population, suggesting their modulatory rather than causal role. However, after the irruption of new genetic techniques in the last 15 years, a greater number of cases are being identified with genetic disorders (many of them monogenic), whose genetic variants alone explain the presence of ADHD. A detailed study of the personal and family history, as well as a complete physical examination, can help to identify some of them. The identification of the cause in this group of cases has a crucial value in clinical counseling, genetic-familial counseling and prognostic anticipation, as well as in the performance or avoidance of complementary studies and in the design of the intervention plan.