“It’s not a coincidence that areas of the body that have undergone more recent evolution are also the areas of the body where we tend to see more human-specific disease. Researchers have been able to connect a lot of particular human-specific gene variants to conditions such as knee pain, low back pain, but in particular, neurological disease,” says Meredith Course, PhD, postdoctoral fellow in the UW Valdmanis Lab, Division of Medical Genetics, who is the lead author of a new study published in the American Journal of Human Genetics that lies at the intersection of genetic sequencing technology, human evolution, and the progressive motor neuron disease amyotrophic lateral sclerosis, or ALS, which affects 30,000 Americans.
The study adds evidence to a hypothesis that while the ancestral human brain expanded over millions of years, parts of some genes related to brain function and behavior expanded in the population as well—literally—growing longer. In rare events, over evolutionary time periods, some of these regions of the genome continued to expand in our ancient relatives, by adding on copy after copy of a repeated segment of DNA nucleotides within the particular gene. In the modern human population, some have continued to lengthen, even to the point of causing disease. While extremely uncommon, more than 40 so-called ‘tandem repeat expansions’, are currently known to cause or increase risk of neurological diseases, such as ALS, in people who carry an expansion with too many copies in it.
Please use the link below to access the full article written by Genevieve Wancucha, Senioir Writer at UW Memory and Brain Wellness Center/ADRC: