Molecular genetics of attention-deficit/hyperactivity disorder: an overview

Abstract

As heritability is high in attention-deficit/hyperactivity disorder (ADHD), genetic factors must play a significant role in the development and course of this disorder. In recent years a large number of studies on different candidate genes for ADHD have been published, most have focused on genes involved in the dopaminergic neurotransmission system, such as DRD4, DRD5, DAT1/SLC6A3, DBH, DDC. Genes associated with the noradrenergic (such as NET1/SLC6A2, ADRA2A, ADRA2C) and serotonergic systems (such as 5-HTT/SLC6A4, HTR1B, HTR2A, TPH2) have also received considerable interest. Additional candidate genes related to neurotransmission and neuronal plasticity that have been studied less intensively include SNAP25, CHRNA4, NMDA, BDNF, NGF, NTF3, NTF4/5, GDNF. This review article provides an overview of these candidate gene studies, and summarizes findings from recently published genome-wide association studies (GWAS). GWAS is a relatively new tool that enables the identification of new ADHD genes in a hypothesis-free manner. Although these latter studies could be improved and need to be replicated they are starting to implicate processes like neuronal migration and cell adhesion and cell division as potentially important in the aetiology of ADHD and have suggested several new directions for future ADHD genetics studies.

The decisions regarding ADHD management (DRAMa) study: uncertainties and complexities in assessment, diagnosis and treatment, from the clinician’s point of view

“…At its core is a persistent and pervasive pattern of inattention, overactivity and impulsiveness (1,2). ADHD often overlaps with other disorders (e.g., conduct disorder, anxiety, dyslexia; (3,4,5) and is associated with significant impairment across functional domains and in quality of life (e.g., home, school, work) (6).…”

Investigation of alexithymia, depression and childhood ADHD symptom levels in parents of children with ADHD

“…Literatürde DEHB'nin kalıtsal aktarılabi-lirliğine ilişkin çalışmalar vardır. [43][44][45] DEHB'li çocukların anne-babalarında erişkin DEHB yaygınlığının ve belirtilerinin arttığı bildirilmiştir. 46,47 Anne-babaların psikiyatrik tanılarını değerlendir-mek için yapılandırılmış bir klinik görüşme tekniği uygulanmamış olması, anne-babalarda şimdiki DEHB belirtilerini değerlendirmek amacıyla bir Anatolian Journal of Psychiatry 2018; 19(4):411-418 ölçeğin kullanılmamış olması, anne-babanın ayrı ayrı değerlendirilmemiş olması, depresyonu yordayabilecek farklı değişkenlerin değerlendiril-memiş olması, aleksitiminin klinik bir görüşmede ele alınmamış olması bu çalışmanın sınırlılık-larını oluşturmaktadır.…”

Genetic Influences on Peer and Family Relationships Across Adolescent Development: Introduction to the Special Issue

“…However, we believe that thoughtful, hypothesis-driven studies are valuable as long as the researchers are cognizant of potential replication problems. Notably, a large number of studies have found that the DRD4 gene, which encodes proteins that respond to the neurotransmitter dopamine in the brain, is related to a number of externalizing types of behaviors, such as novelty seeking, aggression, and hyperactivity (Banaschewski, Becker, Scherag, Franke, and Coghill 2010;Farbiash, Berger, Atzaba-Poria, and Auerbach 2014;Ray et al 2009). Similarly, other genes have been identified repeatedly across different studies, suggesting that they code for neurotransmitter action in the brain that is related to certain behaviors.…”