Inheritance

= Inheritance/Chance =
 * The HD gene is located on the short arm of chromosome 4. It codes for a protein called huntingtin, whose function is not known. Any person with the huntington’s mutation will eventually get the disease in their lifetime.
 * The mutation, or change in the DNA, is rare to obtain because it is the repetition of three genetic bases in a row. Any less repitions does not code for the disease. The mutation is made up of many of these types of repetitions called CAG trinucleotide repeats. Extra nucleotides cause protein huntingtin to contain extra sections as well. This extra (a defect in the Huntington gene) interacts with other proteins in cells to damage the brain which eventually leads to the disease.
 * This repeat determines how severe the disease can be. **The longer the repeated strand, the more severe case of huntingtons is obtained.** This results in an abnormal huntintin protein distributed around the body which is caused by the mutation.
 * The child of someone who has huntingtons has a 50% chance of obtaining the genetic mutation and once they have the mutation, it is for sure they will get the disease in their lifetime. **The HD gene is a dominant gene,** which means it produces a protein and is shown over the recessive trait. It may be inherited from either parent. The chances of passing on the HD gene are not affected by the results of previous pregnancies. HD affects males and females equally and crosses **all ethnic and racial boundaries.**
 * HD does not skip generations. Everyone who carries the gene will develop the disease although you MUST have HD gene to get the disease. If a child didn’t inherit the gene from his/her parents, he/she cannot pass it on to their children. But if the child does inherit the gene, he/she can pass it on and will develop HD if that child lives long enough. Most people die because of medical problems that arise from the HD, not as a direct result of it
 * Other dominant diseases usually do not get passed on to their children because it kills the affected people before the age of reproduction. Huntingtons, on the other hand, kills at the later ages (past 40). This is dangerous for families with previous history of huntingtons because it is easy to be passed on through generations.
 * For Example. (H is dominant affected, and h is not affected recessive) ~ If one person with heterozygous Huntingtons (Hh) mates with a person without Huntingtons (hh), they still have a huge 50% of having a child with the disease. This makes it very dangerous for familys with previous cases of Huntingtons because it is more likly they will pass it on.

= Diagnostics = Scientists still do not know the main cause of huntingtons and there is no cure for the disease just yet. A genetic test is available, though, for the disease but once you have the disease, there is not much yet that the doctors can do. They can only give medicine to lower the “choreiform” movements (occasional jerking or writhing movements) of the person temporarily.