Implications of DNA copy number variations in attention-deficit/hyperactivity disorder: An update review

Abstract

Introduction Attention deficit hyperactivity disorder (ADHD) is a highly heritable disorder. Rare genetic variants, specifically large, rare copy number variants (CNVs) play an important role in ADHD and others neurodevelopmental disorders. Objectives Identify previous studied correlations between CNVs and ADHD, analysing physiological and genetic pathways in association with another neuropsychiatric disorders. Aims Identify most commons CNVs variations present in ADHD; evaluate similarity between results found in researches in relation to pleiotropy and ADHD phenotypes. Methods A scientific originals articles research was conducted on PubMed. Used keywords ‘Attention Deficit Disorder with Hyperactivity' and ‘DNA Copy Number Variations'. Among twenty articles found, published in the last ten years, sixteen articles were selected based on relevance of information. Results Rare CNVs were described in association with ADHD. Almost 44% of the articles reviewed screened CNV regions possibly linked with ADHD pathologic pathways, especially to metabotropic glutamate receptor and genes related to others psychiatric disorders, like PARK2 and SHANK3 . The case control studies also indicate some coexistence of rare and common forms ADHD. Nevertheless, there is not a consensus about relations between CNVs in ADHD samples and intellectual disability. Moreover, all articles suggest a pleiotropic effect related to CNVs in ADHD patients and others neuropsychiatric disorders. Conclusion The relevance of CNVs in ADHD patients is clearly supported by the current findings. However, further research is necessary to analyse CNVs influence in IQ of ADHD individuals. In addition, genotype association studies to clarify the pleiotropies stated are required.