City of Villains

Huntington’s disease progression

Each person has about 30,000 genes–a billion base pairs of DNA or bits of information repeated in the nuclei of human cells–which determine individual characteristics or traits. For some time huntington’s disease was thought to be the only disease for which possession of a second mutated gene did not affect symptoms and progression, but it has since been found that it can affect the phenotype and the rate of progression. Offspring of an individual who has two affected genes will inherit one of them and therefore definitely inherit the disease.
Specifically affected are cells of the basal ganglia, structures deep within the brain that have many important functions, including coordinating movement.