What genes are involved in ADHD

Genetic Causes of ADHD?


Thursday September 30, 2010

Cardiff - Is attention deficit / hyperactivity disorder (ADHD) a genetic brain developmental disorder with a distant relationship to schizophrenia and autism? A study in the Lancet (2010; doi: 10.1016 / S0140-6736 (10) 61109-9) provides indications for this for the first time, but without being able to conclusively prove a genetic origin.

Anita Thapar from the University of Cardiff, explains her working group, suggests that there is a genetic predisposition to ADHD, as well as the fact that if one twin falls ill, the other has a three to four chance of developing ADHD as well compared the genome of 366 ADHD patients and 1156 healthy children.
There was no search for gene variants (SNP) behind which gene mutations could be hidden. Rather, with the support of the Wellcome Trust, deviations in the number of copies in certain DNA sections were sought.

Such copy number variants (CNV, gene copy number variants) were previously found in developmental disorders of the brain, from learning disorders to schizophrenia and autism, without their significance for the disease process being currently clear. To do this, the influence of the individual genes would have to be known.

The researchers found CNV in 15 percent of ADHD patients and 7 percent of controls. The difference was statistically significant, but whether it proves a clinically relevant role of genes in the development of the disease is likely to remain controversial.

Thapar told the press that the study proved beyond doubt the influence of genes on the disease. Other researchers, who have previously looked for the causes in environmental influences, for example in poor upbringing or an unhealthy diet, would have to recognize that they were wrong.

The chair of child and adolescent psychiatry believes that the patients have been wrongly stigmatized. Tim Kendall, a director of the National Collaborating Center for Mental Health (NCCMH), which develops treatment guidelines for the National Institute for Health and Clinical Excellence (NICE), told the BBC that genetic variants could be detected in just one sixth of patients Hardly any evidence that ADHD is a genetic disease. Nor would genes explain why some children develop ADHD and others do not.

It actually seems a bit too early for a general assessment of the study results. In any case, the results of the study have no influence on the diagnosis and treatment of the disease. However, Utrecht University editorialist Peter Burbach hopes that the discovery of CNV will provide insights into the pathogenesis and neurobiology of the disease.

The main research interest is directed to a region of chromosome 16p13,11 where several CNVs have been found. Of particular interest to Burbach is the NDE1 (nuclear distribution gene E homologue 1) gene located in this region, which is apparently involved in brain development.

According to Burbach, it interacts with the DISC1 gene (disrupted in schizophrenia 1), which predisposes to schizophrenia. Most brain researchers today see schizophrenia as a developmental disorder of the brain, which probably also applies to autism, for which, according to the results of the current studies, there is also “CNV overlap” with ADHD.

However, the importance of a possible relationship should not be overstrained. According to Burbach, the CNV explain at most 1 to 2 percent of the cases in schizophrenia and autism. It is likely to be similar with ADHD, even if the authors do not provide any information on this in the study.

© rme / aerzteblatt.de

Genetic Causes of ADHD?

Find out every day (Monday to Friday) by e-mail about current events in health policy and medicine. Order the free newsletter of the Deutsches Ärzteblatt.

Always be up to date without chasing after information: The daily updated newsletter