03/18/2026
What Is Huntington’s Disease?
The Science Behind the Illness That Steals Everything - Dustin Anderson, Director of Advocacy, Take Back Tomorrow HD
Most people have never heard of Huntington’s disease. But for the families it touches, it is impossible to forget — and impossible to escape.
HD is a rare, fatal, inherited neurological disorder that causes the progressive breakdown of nerve cells in the brain. It affects movement, cognition, and behavior simultaneously — robbing people of their ability to walk, speak, swallow, think clearly, and regulate their emotions, all at once.
There is currently no cure, and no treatment that slows its progression.
But to truly understand why HD is so devastating, you have to start at the very beginning — inside your DNA.
The Genetic Culprit: A Repeated Mistake
Every human carries a gene called HTT on chromosome 4. This gene contains a sequence of three DNA letters — cytosine, adenine, and guanine (CAG) — that repeat in a row. In people without HD, this CAG sequence repeats approximately 10 to 35 times. That’s normal.
In people with Huntington’s disease, that CAG sequence repeats 36 times or more. And the longer the repeat, generally the earlier and more severe the disease.
This single mutation — an extra stutter in a three-letter sequence of your genetic code — is all it takes to set the entire process in motion.
What Goes Wrong in the Brain
The HTT gene is responsible for producing a protein called huntingtin. Scientists believe normal huntingtin plays important roles in brain development and function. But when the gene carries the expanded CAG repeat, it produces a mutant huntingtin protein — one that is misfolded, toxic, and relentless.
This mutant protein accumulates in neurons, particularly in a region of the brain called the striatum, which is responsible for coordinating movement, decision-making, and emotional regulation. Over time, it damages and kills these neurons. The brain, quite literally, begins to shrink.
As neurodegeneration spreads, it reaches the cortex — the outer layer of the brain responsible for memory, reasoning, and personality. That’s when families begin to notice changes in mood, impulse control, and cognitive function, sometimes years before any movement symptoms appear.
The Three Faces of HD
Huntington’s disease attacks on three fronts simultaneously:
🔹 Motor symptoms — Chorea (involuntary, dance-like movements), loss of balance and coordination, difficulty swallowing, and eventually the inability to walk or speak.
🔹 Cognitive symptoms — Slowed processing speed, difficulty with planning and organization, memory lapses, and progressive dementia.
🔹 Psychiatric symptoms — Depression, anxiety, irritability, obsessive-compulsive behaviors, apathy, and in some cases psychosis. These are often the first signs of the disease, appearing years before a diagnosis is made.
It’s 100% Hereditary — With 50/50 Odds
Huntington’s disease is autosomal dominant — meaning only one copy of the mutated gene is needed to cause the disease. If a parent carries the HD gene mutation, each child has a 50% chance of inheriting it.
There are no carriers. If you inherit the mutation, you will develop HD — barring some other cause of death first. This creates an agonizing reality for families: watching a parent deteriorate while knowing there is a coin-flip chance that you or your siblings carry the same fate in your own DNA.
Many at-risk individuals choose to live without knowing their genetic status. Others test early, seeking the certainty — however difficult — to plan their lives.
The Timeline of the Disease
HD typically presents in mid-life, most commonly between the ages of 30 and 50, though it can appear earlier (Juvenile HD) or later in life. Once symptoms begin, the disease progresses relentlessly over 10 to 25 years. There is no remission. There is no plateau.
The final stages of HD leave individuals unable to communicate, unable to move independently, and fully dependent on round-the-clock care. The most common causes of death are pneumonia (often from aspiration due to swallowing difficulties), falls, and heart disease.
Where Science Stands Today
The HD research landscape has evolved dramatically in recent years. Scientists now understand the molecular mechanics of the disease with remarkable clarity — which is both a source of hope and, at times, of heartbreak.
Gene-silencing approaches, including antisense oligonucleotides (ASOs) and RNA interference (RNAi), aim to reduce production of the mutant huntingtin protein before it can cause damage. One of the most promising frontiers is gene therapy — the possibility of a one-time treatment that could silence or correct the underlying genetic mutation at its source.
That work is ongoing. And for the families waiting, it cannot move fast enough.
Why This Matters
Approximately 30,000 Americans are currently living with symptomatic HD, and an estimated 200,000 more are at risk due to family history. Globally, that number reaches into the hundreds of thousands. These are parents. Children. Siblings. Spouses.
They are people who woke up one day to learn that the future they had imagined — raising their kids, growing old with their partner, simply being present — had been quietly stolen by a three-letter typo written into their DNA before they were born.
At Take Back Tomorrow HD, we believe that understanding the science is the first step toward demanding better — from researchers, from pharmaceutical companies, and from the regulators who hold the power to accelerate access to treatments that could change everything.
Because knowledge isn’t just power. In HD, knowledge is urgency.
💙 Share this post if you believe more people should understand Huntington’s disease. The more voices we have, the louder the call for action becomes.
