MedicineNet

Even years before HD is typically diagnosed, the brain's already affected.
- Cognitive signs: impaired emotion recognition, mild cognitive impairment
- Behavioral signs: slight increase in risk of mood problems (the risk increases a lot in the year leading up to the diagnosis)
- Motor and physical symptoms are almost always absent at this stage.

Huntington's Disease (HD) | Preclinical Stage (Stage 1)

In this stage, serious behavioral symptoms (e.g., depression, irritability, disinhibition) often occur. Cognitive and motor symptoms become noticeable, although still relatively minor.

Huntington's Disease (HD) | Early Stage (Stage 2)

In this stage, behavioral symptoms (e.g., depression, irritability, disinhibition) are often serious. Motor and cognitive symptoms become problematic. By this stage, usually, patients cannot drive, work, or do household work easily.

Huntington's Disease (HD) | Middle Stage (Stage 3)

In this stage, motor and cognitive symptoms are severe, although behavioral symptoms tend to improve slightly (compared to the middle stage). By this point, patients are unable to work, drive, and do household work. Eventually, patients become bedridden and can't walk and swallow.

Huntington's Disease (HD) | Late Stage (Stage 4)

Huntington's disease has 5 stages. Stage 2 is where HD is usually first diagnosed.
- Stage 1: Preclinical stage
- Stage 2: Early stage 
- Stage 3: Middle stage 
- Stage 4: Late stage
- Stage 5: End-of-life stage

University of Michigan - Ann Arbor

- An Inherited, adult-onset, eventually fatal brain disease.
- About 41,000 Americans have HD symptoms; 200,000 are at-risk of inheriting HD


Huntington's Disease (HD) | Introduction

Note: A basic understanding of cell biology is needed to understand this node.
- Improve resilience/survival of neurons affected by the abnormal (mutated) huntington protein.
- Stem-cell therapy to replace damaged/dead neurons
- Reducing the production of huntington 
- Increasing huntington’s clearance and degradation by inducing autophagy 


Huntington's Disease | Research Directions

- Inherited in an autosomal dominant manner (i.e., one mutant copy of the gene is enough to cause symptoms)
- CAG segment in the gene Huntington is repeated too many times, leading to the formation of an abnormal huntington protein

Genetics of Huntington's Disease

- The striatum -- critical for mood, motor, and behavior control -- is most severely affected, though many other regions get affected in the late stages.
- Hence, motor control (e.g., involuntary movements), behavior control, mental health (e.g., major depression, OCD), and cognition are impaired.
- Patients often describe their condition as having Alzheimer's, Parkinson's, and ALS simultaneously.

Huntington's Disease (HD) | Symptoms and Brain Regions Affected

- The motor (movement-related) symptoms of HD usually start in the 40s and 50s, with other subtle changes possibly starting much earlier.
- However, 10% of patients start to have motor symptoms after age 60, and 10% have juvenile-onset HD (i.e., motor symptoms occur before age 20).

Huntington's Disease (HD) | Age of Onset

- Current treatments cannot even slow HD progression, although they can alleviate HD symptoms.



Huntington's Disease (HD) | Current Treatments

General Sources (e.g., reliable websites, textbooks)
- HOPES (Huntington's Outreach Project For Education) Stanford University
- Huntington's Disease Society of America
- MedicineNet
- Medline Plus | U.S. National Library of Medicine
- Wikipedia

Journals (No journals used yet)

Huntington Disease References

Mutant HTT (huntingtin) directly interacts with p53, a tumor suppressor whose mutation is responsible for breast cancers, in mice and flies. Although not always, the phosphorylation of HTT can also induce neuro protectiveness in individuals with Huntington’s and can help regulate cell differentiation and localization. Overall, there is 80% less rate of cancer amongst people with Huntington's than the normal population.

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