Huntington's Disease

Huntington's disease (HD) is a progressive, inherited neurodegenerative disorder characterized by the deterioration of nerve cells in the brain. It is caused by a faulty gene on chromosome 4, which leads to an abnormal expansion of a DNA segment—specifically the CAG trinucleotide repeat in the huntingtin (HTT) gene. This mutation results in the production of an abnormal version of the huntingtin protein, which disrupts the function and eventually leads to the death of brain cells, particularly in the striatum and cerebral cortex. Symptoms typically emerge in adulthood, around the ages of 30 to 50, although a rare juvenile form can occur.

The clinical manifestations of Huntington's disease are diverse, including uncontrollable jerking or writhing movements (chorea), muscle problems such as rigidity or muscle contracture (dystonia), and poor coordination. It also brings cognitive decline, leading to impaired reasoning, memory loss, and difficulty in planning, prioritizing, and organizing tasks (executive dysfunction). Psychiatric problems are common and varied, ranging from depression, irritability, and apathy to obsessive-compulsive behavior and psychosis. Currently, there is no cure for HD, and treatments focus on managing symptoms. Genetic counseling is recommended for at-risk individuals considering that the disorder is autosomal dominant, meaning each child of an affected parent has a 50% chance of inheriting the condition.