Huntington’s Disease (HD) is a brain disorder

Huntington’s Disease (HD) is a brain disorder that affects a person’s ability to think, talk, and move.

The disease destroys cells in the basal ganglia, the part of the brain that controls movement, emotion, and cognitive ability. HD is caused by a mutation in a gene on chromosome 4. The job of its protein product, huntingtin, is to direct the delivery of small offerings (vesicles containing substantial molecules) to the outside of the cell. Normally, the coding region of this gene contains the DNA sequence “CAG” repeated again and again. The amount of times that triplet is repeated varies from person to person, ranging of 10 to 26 times. People with HD have an abnormally high number of these CAG triplets, roughly 40 or more. This likely disrupts the function of the gene’s protein product, but how the expansion of the CAG repeat instigates disease is unknown. Somehow the brain cells of HD patients accumulate clumps of protein the become toxic, resulting in cell death. Some patients lose a larger number of than 25% of their brain cells before properties die.