Huntington's Disease

Definition

Huntington's Disease is a genetic disorder caused by a mutation in the HTT gene, leading to progressive neurodegeneration and various physical and cognitive symptoms. It is inherited in an autosomal dominant manner, meaning that an affected individual has a 50% chance of passing the disorder to their offspring. The condition exemplifies extensions of Mendelian inheritance, highlighting how genetic traits can manifest in complex ways and impact families across generations.

5 Must Know Facts For Your Next Test

1. Huntington's Disease typically manifests in mid-adulthood, but symptoms can appear earlier or later depending on the number of CAG repeats in the HTT gene.
2. Common symptoms include involuntary movements (chorea), cognitive decline, and psychiatric issues such as depression and anxiety.
3. There is currently no cure for Huntington's Disease, but treatments focus on managing symptoms and improving quality of life.
4. Genetic testing is available to determine if an individual carries the mutation associated with Huntington's Disease, providing important information for family planning.
5. Research is ongoing into potential therapies, including gene editing technologies like CRISPR, which may offer future avenues for treatment.

Review Questions

• How does Huntington's Disease illustrate the concept of autosomal dominant inheritance?
  • Huntington's Disease exemplifies autosomal dominant inheritance because it only requires one copy of the mutated HTT gene for an individual to be affected. If a parent carries the mutation, there is a 50% chance that each child will inherit the disorder. This pattern shows how certain genetic conditions can be passed down through generations, affecting family dynamics and decision-making regarding testing and future children.
• Discuss the role of CAG repeat expansion in the pathology of Huntington's Disease and its implications for genetic testing.
  • CAG repeat expansion refers to the abnormal increase in the number of CAG sequences within the HTT gene, which leads to the production of a toxic protein that damages neurons. The severity and age of onset of Huntington's Disease correlate with the length of these repeats; longer expansions usually result in earlier onset. Genetic testing can identify individuals with these mutations before symptoms develop, allowing for informed decisions about family planning and personal health management.
• Evaluate the potential impact of gene therapy on future treatment options for Huntington's Disease.
  • Gene therapy holds great promise for Huntington's Disease by potentially addressing the root cause of the disorder rather than just alleviating symptoms. Techniques like CRISPR could be used to edit or silence the mutated HTT gene, potentially preventing or reversing neurodegeneration. If successful, these approaches could significantly improve outcomes for patients, providing them with not only extended life but also a better quality of life, thus transforming our understanding and management of genetic disorders.

Related terms

Autosomal Dominant: A mode of inheritance where only one copy of a mutated gene from an affected parent can cause the disorder in the offspring.

CAG Repeat Expansion: The genetic mutation in Huntington's Disease involves an abnormal repetition of the CAG sequence in the HTT gene, leading to the production of a faulty protein.

Gene Therapy: A medical approach that aims to treat or prevent diseases by modifying or manipulating genes, which has potential applications in conditions like Huntington's Disease.