Four gene variants, all members of the glutamate receptor gene family, appear to be involved in vital brain signaling pathways in a group of children with attention deficit hyperactivity disorder (ADHD). The genes involved affect neurotransmitter systems in the brain that have been implicated in ADHD, and now there is a genetic explanation for this link that applies to this subset of children.
ADHD is fairly common and tends to run in families. Though it is considered by many to be the most commonly over-diagnosed disorder, it is thought to affect about 7% of kids of school age and a smaller percentage of adults.
Researchers from the Center for Applied Genomics at The Children's Hospital of Philadelphia conducted whole-genome analyses of 1,000 kids with ADHD compared with 4,100 others of the same age who did not have ADHD. They looked for duplications or deletions of DNA sequences (copy number variations, or CNVs), and then compared the preliminary findings with various cohorts, made up of 2,500 kids with and 9,200 without ADHD. They identified They identified four genes with a considerably greater number of CNVs in the ADHD children. They were all glutamate receptor (GMR) genes. The one with the strongest result was gene GMR5. Members of the GMR gene gamily, aong with genes they interact with, affect nerve transmission, the formation of neurons, and interconnections in the brain. Glutamate is an amino acid and neurotransmitter. The fact that children with ADHD are more likely to have alterations in these genes reinforces previous evidence that the GRM pathway is important in ADHD.
Co-first author Josephine Elia, M.D., says, "This research will allow new therapies to be developed that are tailored to treating underlying causes of ADHD. This is another step toward individualizing treatment to a child's genetic profile."