The Genetics of Huntington’s disease
January 24, 2012
Plenty of people love the fact that they can enjoy a normal life because their brain functions accordingly. Well not everyone has the gift of normality. In this harsh world people are dying of all types of diseases and things that are undetectable or even treatable due to the fact that they have unknown origins. Among these fatal and life threatening ailments, Huntington’s disease, otherwise known as (HD), takes precedence.
A woman stares pensively out her bedroom window. Today is her twentieth birthday. Most people have the whole ...view middle of the document...
Genetic disorder is a disease that is caused by an abnormality in one's DNA. The abnormality, such as mutation, may occur in the single gene as well as in the whole chromosome or in a set of chromosomes. One of the genetic disorders that greatly influence human life is Huntington Disease. Huntington Disease (HD), also called Huntington Chorea, is a brain disorder resulted from a gene mutation in protein called Huntington. The mutation in Huntington causes a progressive degeneration of the neurons in the basal ganglia. The word "chorea" comes from Greek, and means "dance" in Latin. It refers to the uncontrollable movements of the afflicted individual. Even though the disorder is named after George Huntington, he was not the first scientist who witnessed this disease. His famous paper "On Chorea", which was submitted by him in 1872, was the first paper that described Chorea in details. Much of the information for Huntington's paper was drawn from his father's and grandfather's written observations, both physicians who had described the involuntary shaking in patients. The paper gained Huntington instant notability because he was able to clearly point to the genetic inheritance as the mode of transmission, and he also noticed that the first symptoms usually appear in the adult age and are accompanied by a mental decline as well. It is due to these significant observations and conclusions that "Huntington's Disease" bears George Huntington's name. Nowadays, approximately 30,000 people in the United States suffer from HD, with another 15,000 at risk of developing this disorder.
Huntington’s disease is a fatal inherited disorder characterized by slow gradual personality changes, dementia, and chorea form movements. It is a progressive disease; its average onset is thirty to forty years of age, and the duration of the disease is about ten to twenty years with death as the outcome. It is known that for Huntington’s disease, there is a degeneration of cholinergic and GABAergic neurons in the basal ganglia and the cerebral cortex. (Ball, Harper 1992) The etiology of nerve cell death in Huntington’s disease is unknown. However, there is a recent hypothesis implicating defects in mitochondrial energy metabolism as the pathology of Huntington’s disease. Huntington’s disease is an autosomal dominant disease. The genetic defect appears on the short arm of the chromosome 4, and it is an extended repetition of the three nucleotide bases (cytosine, adenine, and guanine; CAG) that code for the amino acid glutamate. This disease affects men and women equally, and it usually appears after the individuals have married and had children. Each child of a person who has HD has a 50% chance of inheriting the disease, and the disease does not skip a generation. Also, each of that child's' children will have a 50% chance of inheriting the gene, and so on and so forth. If you do not have the HD gene you can't pass it on to your children and if your mate doesn't have it...