HD isn't always High Definition
Double Helix
One day, while I was volunteering at a local library. I came across a book called “Double Helix” (Nancy Werlin) which opened my eyes to a disease called Huntington’s disease or HD. It got me wondering, “What exactly is this disease and how is it transmitted?” I looked this up and got an extremely complex answer. I understood it after reading it five or six times, but for everyone else, I’ll break it down for you.
History
HD dates back to the Medieval Times when sickness ran around the town like ants to a picnic. It was finally diagnosed in 1872 by a man named George Huntington. It was defined as chorea for a time, but was changed to the disease more commonly known, as I said before, as Huntington’s Disease.
The Basics of HD
Now, DNA is composed of four genes: Adenine, Thymine, Cytosine, and Guanine (abbr. A, T, C, G). You’re DNA is divided into 23 chromosomes. Just remember this while I make an analogy.
DNA is a long (extremely long) coded message that tells your body what to do, how to do it, and when. Just like the alphabet, these genes make different words for the body to follow. This is what makes us different from one another. Because we are different, we have pattern combinations, but we shall only go over one today. That pattern is C, A, G which is found in the fourth chromosome of your 23.
If you’re worried that you may have this pattern, don’t worry about it. Everyone has this pattern in their DNA. It’s almost unavoidable. Most people have around 10-35 repeats of this genetic pattern. That’s the normal number, but it can vary from person to person. If people have 36-120 repeats of this pattern; that is when they will most likely experience symptoms of this disease in their middle ages.
The Uniqueness of HD
HD is very different, as is every disease; but in this case, how you can get it is interesting. You see, you’re parents have two copies of the same genes, but they each give one of them to you. One could be dominate (ex. Brown hair) and the other could be recessive (ex. Red hair). You may or may not get both, but only one will show. You will for certain get at least one of each of your parent’s genes.
HD is a gene that is categorized as an autosomal dominant disorder. This means that you will only need one gene of HD to have this disease. This also means that if a sibling of yours has HD, and you do not, you are still at risk of passing on the disease to your children. It does not skip generations, so anyone in your family could have it depending on which side the disease originated from.
-less than or equal to 28: no HD, will not pass on to children
-29-34 repeats: will not develop HD, but children may
-35-39 repeats: some people in this generation will develop HD, children may develop.
-more than 40: will develop HD
Symptoms
The symptoms of HD can be seen anytime, but is more commonly seen in people from the ages of 35-40. The earlier the development, the faster the disease cycle will take place.
Children who develop the symptoms at an early age (before 20) have inherited HD from their fathers. They will have a rapid decline in school, handwriting changes, and slight problems with movement. They are also liable to having seizures and mental disabilities. They will probably not survive the next 10 years.
People who develop the disease in their middle ages will have mood swings, become irritable, angry, passive, apathetic, and/or become depressed. Mental capacity and activity will also fall, followed by physical activity. It also may be developed with cholera (fatal intestinal disease) or akinesia (rigid/limited movements). People who develop this disease without cholera will most likely survive and deaths would be from infections or injury from falling. The illness usually lasts from 10-30 years.
It is hard to diagnose people who develop this disease in people over 55 due to other health issues that may possibly be developed. They usually show signs of depression rather than anger. They may also retain their ability to reason, problem-solve, and memory. They may often develop a string of cholera called senile cholera which is involuntary movements.
Diagnostics &Treatment
First you would want to schedule an appointment with a neurologist and they will ask you questions about your family history and rule out ways you may possibly inherit it. You must be as truthful as possible while answering these questions if you are serious on finding out how you may or may not get it. A doctor will also ask questions about recent emotional and physical abnormalities followed by tests for hearing, eye movements (people with HD have a hard time following a target), strength, coordination, etc. After all this, the doctor will probably order several lab tests including a blood test (to determine how many repeats of C, A, G there are) CT, MRI, and/or PET* scans. This is all optional, and some people do not wish to find out if they have HD or not.
*PET scans are important in HD research, but are not needed in diagnosing the disease.
To Learn More About this visit:
http://www.medicinenet.com/huntington_disease/article.htm
http://www.umm.edu/ency/article/000770.htm
