Mice Help Scientists Understand ALS and Frontotemporal Dementia
Research that made its debut at the RNA Metabolism in Neurological Disease conference in Chicago in October 2015 is helping scientists understand amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). ALS affects between 20,000 and 30,000 people in the U.S., killing the nerve cells in their spines and causing paralysis and death within a few years. A similar number of people develop frontotemporal dementia, in which the nerve cells that control behaviors, personality or language degenerate. ALS and FTD can both result from a DNA expansion in a gene on chromosome nine, called C9ORF72. This happens when repeat sequences of six DNA bases (GGGGCC) grow from a handful into hundreds or thousands of copies. Sometimes these conditions co-exist, and they can be caused by the same genetic mutations, such as those in C9ORF72. During their study, researchers engineered mice to have either a partial or complete C9ORF72 gene. The mice with the partial gene were healthy; they moved around and behaved normally, and lived normal lifespans, even though they produced RNAs and proteins from the repeats. Only some of the mice with the full C9ORF72 gene plus repeats got sicker. These animals lost weight and had trouble moving; many died early. Researchers are not sure why these mice experienced a more severe disease. Other mice with the full gene and many repeats seemed unaffected, leaving scientist to surmise that some additional factors, such as age or environmental stresses, might conspire to cause ALS and FTD. To read more about this study, click here.
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