News: Specialized Press
Genetic variations are found to occur more frequently in children with attention deficit with hyperactivity disorder (ADHD)
Source: MOLECULAR PSYCHIATRY in advance. 2009 JUN: 19546859. / Date: JUNE 2009 / Category: Specialized Press
Researchers at The Children's Hospital of Philadelphia, in the United States, have identified hundreds of genetic variations that occur more frequently in children with attention deficit with hyperactivity disorder(ADHD). Many of these genes are already known and are important for learning, behavior, brain function and neurodevelopment but they had not been associated with ADHD before. The study results are published this week in the journal 'Molecular Psychiatry’.
According to Josephine Elia, director of the study, "because the genetic alterations found are involved in the development of the nervous system, they could guide researchers to earlier interventions in children with ADHD."
Unlike the changes in single bases of DNA, called single nucleotide polymorphisms or SNPs, alterations in the current study are broader changes in the structure known as variations in the number of copies (VNC).
These VNC are pieces of DNA that are not there or are repeated, and often have an important role in many diseases, including autism and schizophrenia.
All people carry these VNC in their DNA but not all of these variations occur in locations that affect the functioning of a gene. Individually, each VNC might be rare but in combination a combination of changes in critical regions might interact and increase the risk of an individual for a specific disease.
The researchers analyzed the genomes of 335 patients with ADHD and their families and compared them with more than 2,000 healthy children without a family history. The results showed a similar amount of VNC in each group but different patterns emerged.
Among the 222 hereditary VNC discovered in families with ADHD and not in healthy individuals, a significant number were genes previously identified in other neuro-developmental disorders such as autism, schizophrenia and Tourette's syndrome. The VNC discovered in families with ADHD also altered genes in neurological and psychological functions such as learning, behavior, synaptic transmission and nervous system development.
According to the researchers, some of the biological mechanisms involved in ADHD could also be common to other neurological disorders. Similarly, there are some overlaps among the VNC found in ADHD that also occur in autism, schizophrenia and other neurological disorders.
According to Elia, this overlap is not surprising because patients with ADHD also often have one or more of these disorders. However, as researchers discover more about the specific genes of neurological disorders, the hope is that we can customize future treatments for each genetic profile.