What type of genetic cause did Rosa Rademakers and Bryan Traynor independently discover for ALS and frontotemporal dementia, earning them a Breakthrough Prize in April 2026?

The genetic cause discovered independently by Rosa Rademakers and Bryan Traynor for amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), which earned them a Breakthrough Prize in April 2026, is a mutation in the C9orf72 gene. This significant finding, made in 2011, identified a common genetic link between these two devastating neurodegenerative conditions, which were previously often studied separately. Their work revealed that this particular mutation is the most common inherited cause of both ALS, also known as Lou Gehrig's disease, and FTD, the second leading cause of early-onset dementia.

The C9orf72 mutation involves a specific type of genetic error known as a hexanucleotide repeat expansion. Normally, a short segment of DNA, specifically the sequence "GGGGCC," is repeated a small number of times, typically between two and twenty, within the C9orf72 gene. However, in individuals with this mutation, this sequence is abnormally repeated hundreds or even thousands of times. This excessive repetition disrupts the normal function of cells, leading to a reduction in the production of the C9orf72 protein, which is crucial for cellular waste removal, and also results in the creation of toxic (Review) proteins. These cellular disruptions ultimately damage nerve cells in the brain and spinal cord, contributing to the symptoms of ALS and FTD.

The independent discovery by Dr. Rademakers, then at the Mayo Clinic, and Dr. Traynor, from the National Institute on Aging, National Institutes of Health, fundamentally reshaped the scientific understanding of these diseases. By establishing a shared genetic origin, their research provided crucial answers for families affected by inherited forms of ALS and FTD. This breakthrough has paved the way for more accurate diagnoses, improved genetic counseling, and significantly accelerated global research efforts aimed at developing targeted therapies to address the root causes of these complex conditions. Their pivotal contribution to neurodegenerative disease research was recognized with the prestigious 2026 Breakthrough Prize in Life Sciences.