What is Huntington’s Disease (HD)?

About Huntington’s Disease:

• HD is an inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die.
• It has a wide impact on a person's functional abilities and usually results in movement, thinking (cognitive), and psychiatric disorders.
• There are two types of HD:
  • Adult-onset is the most common. Persons with this form usually develop symptoms in their mid-30s or 40s.
  • Early-onset affects a small number of people and begins in childhood or in the teens.
• Cause:
  • A genetic change (mutation) in the HTT gene causes HD.
  • The HTT gene makes a protein called huntingtin. This protein helps your nerve cells (neurons) function.
  • The normal HTT gene contains a stretch of DNA that specifies the number of times the amino acid glutamine is repeated in the Htt protein. This number varies from 11 to 31.
  • In the mutant versions of the HTT gene, this stretch is expanded to encode 35 or more repeats. 
  • As the number of repetitions increases, the severity of Huntington’s disease increases and its debilitation begins at an earlier age.
• HD is rare. The disease is passed down through families.
• Symptoms:
  • HD usually causes movement, cognitive, and psychiatric disorders with a wide spectrum of signs and symptoms.
  • The patient suffers mood swings, has difficulty in reasoning, shows abnormal and uncontrollable jerky movements, and experiences difficulty in speaking, swallowing, and walking.
• Treatment:
  • There is no cure for HD. There is no known way to stop the disease from getting worse.
  • The goal of treatment is to slow the symptoms and help the person function for as long as possible.

Q1: What are neurons?

Neurons (also called neurones or nerve cells) are the fundamental units of the brain and nervous system, the cells responsible for receiving sensory input from the external world, for sending motor commands to our muscles, and for transforming and relaying the electrical signals at every step in between.

Source: Scientists develop new methods to detect Huntington's disease progression