Children’s Hospital of Philadelphia (CHOP), has discovered that there may have been key genetic differences in attention-deficit/hyperactivity disorders (ADHD) among African Americans and people of European descent. This could play a significant role in how patients of various ethnic backgrounds respond to treatment. The journal published the findings online. Scientific Reports.
Previous studies have shown that structural variants in the genome may play an important role for ADHD. These studies were primarily focused on coding regions. This is the DNA or RNA regions that code for specific proteins. They were also conducted primarily in Europeans.
“We felt that previous studies of ADHD from a genetic level were not telling all the story because of who they were leaving off and what they were studying,” said Hakon Hakonarson MD and PhD, Director of Center for Applied Genomics at the CHOP Research Institute and senior researcher of the study. “Given the large number African American people we have recruited to our studies, whose genomes were fundamentally more complicated than those of European bloodlines, we wanted the possibility of comparing the coding/non-coding regions of the genome in those with African American and European ancestry to help us identify areas of focus for our future research efforts.”
The CAG team and their collaborators compiled whole genome sequence data for 875 participants, which included 205 ADHD patients and 670 non-ADHD controls. African Americans accounted for 116 of the 205 ADHD cases and 408 of those who were not diagnosed with ADHD.
The researchers discovered 40 new structural variants in ADHD patients. They also confirmed several structural variants that were associated with ADHD. They identified a cluster structural variants in the noncoding region of pathways that are involved in neuronal brain function. These variants are highly relevant to the development and expression of ADHD phenotypes.
There was only a small overlap (around 6%) in genes impacted by single nucleotide variations between European and African American ancestry. These differences were most evident in the non-coding, structural variants. These variants could also affect how ADHD patients respond to medication.
Hakonarson stated, “Whole genome sequencing seems to be a valuable discovery instrument for studying molecular mechanisms behind ADHD.” “Additionally, the study of non-coding areas of the genome and the inclusion of African Americans in the analysis revealed several structural variants that warrant further investigation as they may have an impact on ADHD susceptibility and patient response to treatment.
Materials provided by Children’s Hospital of Philadelphia. Note: Content may be edited to improve style and length.