Who is likely is to get the disease?
Huntington is a terrible disease that affects the brain. It affects 3-7 people per 100,000 of European descent. It is most common for people of European background to get this disease. This may be because in the past, the disease only affected people who lived in the conditions and weather Europe has, making the disease prominent in Europe. The disease was then passed down through the generations of European people and now most commonly affects them as it's in their genes, although it still affects all ethnicities.
Effects on the body
Huntington disease progressively affects brain cells, either killing or damaging them, this causes uncontrolled movements, emotional problems, and the inability to think. This is also referred to as cognition, which makes people unable to acquire and understand knowledge.
How the disorder is genetically transferred from parent to offspring?
An offspring of someone with Huntington disease has a 50% chance of inheriting the disease. It is an autosomal dominant disorder, which means only one out of the two chromosomes inherited by both parents is needed to create the disease.
A mutation in the HTT gene is what causes Huntington disease. The mutation occurs when there is a DNA segment known as CAG trinucleotide repeat. Ultimately, this is when cytosine, adenine and guanine are repeated multiple times in a row. It is normal for it to repeat from 10-35 times, but for Huntington disease sufferers, it occurs between 36 and more than 120 times. This increased CAG segment of DNA produces abnormally long huntingtin proteins, which split and disrupt cells of the brain.
Is the disease autosomal or sex-linked
The disorder is autosomal as chromosome 4 produces the huntingtin protein, chromosome 4 is non-sex so is autosomal-linked. As it is not a sex-linked disease, the sex of a person doesn't affect the possibility to inherit the disease.
When and how the disorder can be detected?
The disease is progressive, so is usually only detected in the middle ages of life (20 and older.) Once symptoms are detected, it is expected for a person to live 15-20 years. To detect it, you can see if you obtain some of the symptoms, get a genetic test, or check your family's history with this disease. Symptoms include:
-Twitching and jerking
-Lack of coordination
-Speech and swallowing difficulties
-Short term memory loss
There are two types of Hungtington disease, the common adult onset disease, and the juvenile disease. Juvenile starts earlier, and give the affected only around 10-15 years after symptoms are detected, therefore is much more damaging, but, luckily it is very rare.