Huntington's Disease

Definition

Huntington's disease is a genetic disorder that causes the progressive breakdown of nerve cells in the brain, leading to cognitive decline, movement disorders, and emotional disturbances. This disease is caused by a mutation in the HTT gene, which results in the production of a toxic protein that gradually damages neurons. The condition is inherited in an autosomal dominant pattern, meaning that an individual only needs one copy of the mutated gene from an affected parent to develop the disease.

5 Must Know Facts For Your Next Test

1. Symptoms of Huntington's disease typically appear in mid-adulthood, around ages 30-50, but can occur earlier or later.
2. Common symptoms include chorea (involuntary movements), psychiatric issues like depression or anxiety, and cognitive decline affecting decision-making and memory.
3. Currently, there is no cure for Huntington's disease, but treatments are available to help manage symptoms and improve quality of life.
4. Genetic testing can confirm the presence of the mutated HTT gene, allowing individuals at risk to make informed decisions about family planning and lifestyle choices.
5. As the disease progresses, patients may require comprehensive care involving physical therapy, counseling, and support from caregivers and healthcare providers.

Review Questions

• What are the implications of Huntington's disease being inherited in an autosomal dominant manner for affected families?
  • Since Huntington's disease is inherited in an autosomal dominant manner, each child of an affected parent has a 50% chance of inheriting the mutated gene. This means that families face significant emotional and social challenges due to the potential for multiple generations being affected. The knowledge of this inheritance pattern can lead to difficult conversations about genetic testing and family planning decisions.
• How does the CAG repeat expansion in the HTT gene contribute to the pathophysiology of Huntington's disease?
  • The CAG repeat expansion in the HTT gene leads to the production of an abnormal version of the huntingtin protein, which aggregates and becomes toxic to neurons. This toxicity results in neurodegeneration, affecting regions of the brain responsible for movement control, cognition, and emotional regulation. The more CAG repeats present, the earlier symptoms typically manifest, illustrating a direct relationship between genetic mutation and disease progression.
• Evaluate the current treatment options for Huntington's disease and their effectiveness in managing symptoms.
  • Current treatment options for Huntington's disease primarily focus on managing symptoms rather than curing the condition. Medications can help alleviate chorea, mood disorders, and cognitive difficulties. While these treatments can improve quality of life and assist with daily functioning, they do not slow down or halt the progression of neurodegeneration. Ongoing research into therapies targeting the underlying genetic causes holds promise for future advancements in treatment strategies.

Related terms

Autosomal Dominant: A pattern of inheritance where only one mutated copy of a gene from an affected parent can cause the trait or condition to manifest in offspring.

Neurodegeneration: The progressive loss of structure or function of neurons, leading to conditions such as Huntington's disease, Alzheimer's, and Parkinson's.

CAG Repeat Expansion: A specific type of mutation characterized by the repeated sequence of nucleotides 'CAG' in the HTT gene, which leads to the production of a dysfunctional protein associated with Huntington's disease.