2:05 AM
McGhori
Four variants in brain pathways have provided a link between ADHD and genetics.
Researchers from Children’s Hospital of Philadelphia have identified four specific gene variations involved in brain signaling pathways that provide evidence of a link between attention-deficit/hyperactivity disorder (ADHD) and genetics. The findings, which were recently published in the journal Nature Genetics, also offer clues for treatment of the disorder.
ADHD is the most commonly diagnosed behavioral disorder among children, affecting an estimated 3 to 5 percent of school-aged children, according to the U.S. National Library of Medicine. The disorder is characterized by difficulties with attentiveness, over-activity, impulsivity, or a combination of these, and is diagnosed far more often among boys than in girls.
In a written statement, lead study author Dr. Hakon Hakonarson, director of the Center for Applied Genomics at Children’s Hospital, said, “At least 10 percent of the ADHD patients in our sample have these particular genetic variants…. The genes involved affect neurotransmitter systems in the brain that have been implicated in ADHD, and we now have a genetic explanation for this link.”
For their study, the researchers analyzed the whole genomes of 1,000 children diagnosed with ADHD, and another 4,100 children who did not have the disorder. The focus of the study was to identify differences in the number of deletions or duplications of DNA, known as “copy number variations,” among the study subjects.
Findings showed that the children with ADHD possessed a considerable number of differences on four specific genes among the glutamate receptor (GMR) gene family, which are involved in a pathway believed to relay information between the neurons and the brain. The neurotransmitter glutamate is a protein that transmits signals between neurons in the brain.
The research team evaluated their findings based on previous research involving nearly 12,000 participants, among whom 2,500 had ADHD and 9,200 did not. The results revealed that at least 10 percent of those children having ADHD had copy number variations in the four genes identified, with the strongest result occurring in a gene called GMR5.
In the news release, Dr. Hakonarson explained, “Members of the GMR gene family, along with genes they interact with, affect nerve transmission, the formation of neurons, and interconnections in the brain, so the fact that children with ADHD are more likely to have alterations in these genes reinforces previous evidence that the GMR pathway is important in ADHD. Our findings get to the cause of the ADHD symptoms in a subset of children with the disease.”
The study findings could lead to the development of new drugs that would target these pathways to provide more effective treatment for ADHD.
In the statement, study co-author Dr. Josephine Elia, a child psychiatrist and ADHD expert at Children’s Hospital noted, “This is another step toward individualizing treatment to a child's genetic profile.”
Over 5.2 million children between the ages of 3 and 17 have been diagnosed with ADHD in the United States alone, according to the CDC. In addition, the prevalence rate in adults has been estimated at between 2 and 7 percent. The study offers hope for those living with the disorder to lead more normal and productive lives.
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