Huntington’s disease, an inherited condition, causes the progressive degeneration of nerve cells in the brain. It affects an estimated 3 to 7 people of European ancestry per 100,000.
Symptoms progress slowly, normally starting in an individual’s 30s or 40s; they include movement problems, such as jerking or writhing motions, and abnormal eye movements.
There are also cognitive symptoms, including problems organizing and focusing, and a lack of impulse control.
The degeneration of brain tissue in Huntington’s can also produce psychiatric effects, such as depression, insomnia, and social withdrawal.
Huntington’s disease is an autosomal dominant disorder, meaning it is caused by the inheritance of just one copy of a defective gene, rather than a pair. The gene in question is HTT, which codes for a protein called huntingtin.
Although the exact role of huntingtin is not known, it is presumed to be important for the function and development of neurons.