Pediatric researchers at Children’s Hospital Philadelphia have discovered that there are hundreds of gene variations seen more often in children with ADHD than children who do not have the disorder.
Lead researcher Josephine Elia, MD, a psychiatrist and ADHD expert at Children’s Hospital, and her team found 222 inherited copy number variations (CNVs) in children with ADHD, but not in children without the disorder. The CNVs also altered genes that play an important role in psychological and neurological functions like learning, behavior, synaptic transmission and nervous system development.
"When we began this study in 2003, we expected to find a handful of genes that predispose a child to ADHD," said study co-leader Peter S. White, Ph.D., a molecular geneticist and director of the Center for Biomedical Informatics at Children's Hospital. "Instead, there may be hundreds of genes involved, only some of which are changed in each person. But if those genes act on similar pathways, you may end up with a similar result—ADHD. This may also help to explain why children with ADHD often present clinically with slightly different symptoms."
According to the researchers, “a significant number” of the 222 inherited CNVs discovered in children with ADHD are also in genes that have been identified in other neurodevelopmental disorders like autism, schizophrenia, and Tourette’s syndrome.
The study utilized DNA samples from the hospital’s pediatric network, which allowed researchers to analyze the genomes of 335 ADHD patients and their families in comparison to over 2,000 unrelated healthy children. The team used “highly automated gene-analyzing technology” at the Center for Applied Genomics at Children's, which was directed by Hakon Hakonarson, MD, PhD, a co-leader of this study.
"Because the gene alterations we found are involved in the development of the nervous system, they may eventually guide researchers to better targets in designing early intervention for children with ADHD," said Elia, though the researchers emphasized that “much further work must be done before genetic findings lead to ADHD treatments.”
Findings of the study were published online in the journal Molecular Psychiatry.