The genomic revolution is uncovering more and more information about the genetic basis of human diseases. Our DNA is the code for who we are, and it’s copied many times and present in every cell in our bodies. With advances in genomic science, we’re learning more about what our DNA means and what each piece of it does. Many times, this means we can identify changes in DNA sequences that are responsible for specific diseases. These changes from the normal sequences are called mutations or variations, and their effects are often minor but they can be deadly. You may have heard of a mutation that can have a devastating effect on women’s health — the BRCA mutations associated with a heightened risk of breast cancer.
Other DNA sequence changes may only result in subtle changes in how our bodies work. These small changes also explain why we’re all different. These minor changes are called gene variants. However, sometimes multiple gene variants in the same person may result in a disease. As you might imagine, the way that multiple gene variants can combine to result in a disease is a puzzle for scientists to solve.
The widespread ability to sequence human genomes is offering new approaches to understanding disease. The use of genomic science to analyze thousands of human genomic sequences is revealing new insights into disease. Recently, a broad group of scientists from the Danish Aarhus University, MIT, SUNY Upstate University and others have pooled their efforts to identify gene variants associated with attention deficit hyperactivity disorder (ADHD).
Mental disorders have increasingly been identified with multiple genetic variations. It’s estimated that upwards of 75 percent of cases are caused by genetic variations. For this study, the genomes of 20,000 people with ADHD were compared to 35,000 who don’t have the disease. These large numbers allowed the scientists to look closely at the genomic sequences and identify genomic changes that could explain the disease. Their results identified 12 areas of genetic variation linked to ADHD. This means that these areas are different between those with and without the disease. It turns out that people that have more of these gene variants have a higher probability of showing characteristics of ADHD.
The genes with variations in ADHD patients provide some clues to the molecular origin of the disease. For example, some of the gene variants are those that normally allow brain cells to communicate with each other. If the gene variants result in some alteration in that communication, this could start to explain some of the brain changes we see. Other groups of genes that are altered in those with ADHD play a role in language and learning cognitive functions, affect inattention and impulsivity and overlap with genes that affect educational performance.
The study also found a correlation between ADHD and obesity and type II diabetes. Overall, this genomic study sheds light on the biology of the disease and may help provide new clues on how to help those with this disease.