Genes are the instructions cells use to build and regulate the molecules that keep the body alive. A useful way to understand this is the central dogma of biology: DNA is transcribed into RNA which is translated into protein. Proteins then carry out most of the work inside cells, including energy production, structural support, signaling, and waste clearance. When a gene is altered, the resulting protein may be missing, unstable, overactive, or produced in abnormal amounts. In the nervous system, even small disruptions can have major consequences because neurons are long-lived, highly specialized cells that depend on proper maintenance over decades.

Genetics plays several different roles in neurodegenerative disease. Some mutations are causal, meaning they can directly lead to disease, like with HTT and Huntington’s disease. Other variants are risk factors, meaning they increase the likelihood of disease but do not guarantee it, like APOE ε4 in Alzheimer’s disease. Genetic discoveries are important because they reveal which cellular systems are most vulnerable, why people with similar diagnoses may have different disease courses, and why future treatments may need to be increasingly personalized.

​

​