Scientists have discovered an additional potential cause of the genetic mutations that result in rare conditions such as Huntington’s disease (HD). The neurodegenerative diseases, which also include most spinocerebellar ataxias (SCAs), are known to be caused by an expansion in the CAG (cytosine-adenine-guanine) repeats within a gene that in turn leads to an expanded polyglutamine (polyQ) tract in a protein. Such diseases are inherited, given that the expansion of CAG repeats in a gene can be passed down the generations. Previously, it had been thought the damage in these genetic diseases was caused solely by increased protein aggregate toxicity. However, a new study has found an additional source--ribonucleic acid (RNA)--can generate the levels of toxicity to cause damage to the brain in these diseases. Published on August 17, 2023 in Nature Chemical Biology, the research has revealed that expanded CAG repeat RNA can form RNA aggregates in the cytoplasm through a process called liquid-liquid phase separation and gelation. This reduces global protein synthesis, and leads to neurotoxicity and neurodegeneration. The article is titled “Gelation of Cytoplasmic Expanded CAG RNA Repeats Suppresses Global Protein Synthesis.”