What role does the HTT gene play in Huntington's disease?

Understanding the HTT Gene

The HTT gene, short for huntingtin, plays a crucial role in cellular processes within the human body, particularly in the brain. It is located on chromosome 4 and provides instructions for creating the huntingtin protein. This protein is essential for normal development and function of nerve cells, although its complete range of functions is not fully understood. The huntingtin protein is involved in intracellular transport, neurotransmitter release, and other critical cellular activities.

HTT Gene and Huntington's Disease

Huntington's disease is a neurodegenerative disorder characterized by the progressive breakdown of nerve cells in the brain. The HTT gene is directly linked to the development of this condition. The disease is caused by a mutation in the HTT gene that involves an abnormal expansion of the CAG trinucleotide repeats. Normally, this segment of the gene is repeated 10 to 35 times, but in individuals with Huntington's disease, it is repeated 36 to over 120 times, leading to the production of a mutant huntingtin protein.

Effect of the Mutant Huntingtin Protein

The mutant huntingtin protein has a toxic effect on neurons, particularly in certain areas of the brain such as the striatum and cerebral cortex, leading to the characteristic symptoms of Huntington's disease. These symptoms include movement disorders, cognitive decline, and psychiatric problems. The mutant protein accumulates inside nerve cells, causing them to malfunction and eventually die. This neuronal death leads to the progressive declines seen in individuals with the disease.

Inheritance and Genetic Testing

Huntington's disease is inherited in an autosomal dominant pattern, meaning a person only needs one copy of the mutated gene to develop the disorder. Each child of an affected parent has a 50% chance of inheriting the deleterious HTT gene mutation. Genetic testing is available to determine the presence of the Huntington's-causing mutation in individuals, which can confirm a diagnosis or indicate whether someone is at risk of developing the disease in the future. This test is critical for family planning and understanding disease prognosis.

Current Research and Therapeutic Approaches

Research into Huntington's disease and the function of the HTT gene is ongoing. Scientists are exploring various therapeutic approaches to address the effects of the mutant protein and the resulting neuronal damage. Gene silencing techniques, for example, aim to reduce the production of the mutant huntingtin protein. There is also interest in developing drugs that can prevent the toxic effects of the protein or enhance cellular repair mechanisms. These research efforts strive to improve the quality of life for those affected and ultimately find a cure.