More Research Connects Genes to ADHD

According to a recent study, attention-deficit/hyperactivity disorder (ADHD) may be associated with deviations observed in genes which are connected to brain signaling pathways.

This study conducted by researchers from the Children’s Hospital of Philadelphia, also suggests that drugs which influence these pathways may become a new treatment option for ADHD patients with the gene variants.

ADHD is a neurological disorder which affects roughly 7% of school-age children and a tiny percentage of adults. While it is not known why ADHD occurs, it has a tendency to run in families, and is believed to be influenced by many interacting genes.

The researchers performed whole-genome analyses of 1,000 children diagnosed with ADHD and 4,100 children without ADHD. Afterwards they compared the findings with other research which was conducted with 2,500 participants who had ADHD and 9,200 who did not.

The genomic analysis performed by the researchers showed that at least 10% of children who suffer from ADHD have “copy number variations,” meaning they suffer from deletions or duplications of DNA sequences in four genes that make up a section of the glutamate receptor gene family. The strongest correlation seen throughout the study was in gene GMR5.

"Members of the GMR gene family, along with genes they interact with, affect nerve transmission, the formation of neurons, and interconnections in the brain,” explained Dr. Hakon Hakonarson, “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," continued Hakonarson, who is also the director of the Center for Applied Genomics at Children's Hospital.

Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven & Alexandra Cohen Children's Medical Center of New York, reported, "This study provides further evidence not only that ADHD has a genetic basis in a distinct subset of children with ADHD but that the neurotransmitter glutamate seems to play a big role in some cases.”

"This study is important not only in that it has identified gene variants that are associated with ADHD in approximately 10 percent of cases,” Adesman continued, “but it identifies novel treatment strategies related to the neurotransmitter glutamate that researchers can now try to develop for individuals with the newly identified gene variants.”

Adesman stated that comparative whole-genome analysis "may in the future identify other treatment opportunities for sub-groups of children with ADHD and other conditions."

"Hopefully,” he concluded, “these findings will allow researchers to identify safe and effective treatment strategies for the subset of children with ADHD who have variations in their glutamate-related genes."

The study was published online December 4^th in the journal Nature Genetics.