Disease Research

Sherman Chen 3B

Disease Research

Sherman Chen

Biology 2 - 3B

Mr. Boyer

March 10th, 2011 Sherman Chen 3B Huntington’s Disease

Huntington’s disease, chorea, or disorder (HD), is a genetic neurological disorder of the central nervous system that causes progressive degeneration of cells in the brain. The disease results to chorea and dementia, the slowly weakening a person’s ability to walk, think, talk and reason, and it eventually leads to death. The disease was named after Dr. George

Huntington, who first described it in 1872. It destroys cells in the basal ganglia (shown in the picture on the right), the part of the brain that controls movement, emotion, and cognitive ability; therefore a person with HD slowly develops abnormal movements and changes in behaviour and personality.

The beginning of the symptoms of HD is usually shown between the ages of

30 and 50, although 5-10% of the people do start to show the symptoms in late childhood or early adolescence. It normally begins with short-term memory lost or confusion, changes in personality, aggressive and antisocial mood change, and uncontrollable muscle movements. As disorder gets worse, symptoms such as loss of rational thought, poor concentration, difficulty with speaking, and depression can occur. Symptoms normally develop gradually over months or sometimes even years; the person can probably live for another 15 to 20 years after the first symptoms started to show. In the U.S., approximately 1 in every 30,000 people has

Huntington’s disease. Sherman Chen 3B A defect in the gene for a protein of unknown function called huntingtin on chromosome 4 is the cause of Huntington’s disease (shown in the picture below).

Normal huntingtin genes have 30 of “CAG repeats,”, which are DNA nucleotides or the building blocks of genes, but in a defective gene there are 40 or more of these “CAG repeats”. The extra protein section interacts with the proteins in the brain cells, which ultimately leads to cell death. This is what leads to the damage of the nerve cells in the brain. HD is mainly a trait that runs within a family; only in 3% or less of the cases a person has no family history of

HD and the genetic fault is a new mutation. The disease can’t be prevented from developing if the person has the defective gene.

The gene only has to come from one parent in order for the person to inherit the illness and there is a 50% possibility of the offspring inheriting it from the parents.

This makes HD autosomal dominant (a pedigree on the right shows this). Sherman Chen 3B An amniocentesis can be done to identify HD before birth; amniocentesis is a medical procedure in which a small amount of amniotic fluid is extracted from the amniotic sac surrounding a developing fetus to find chromosomal abnormalities. The tragedy of HD is that by the time symptoms have developed, the person with HD already has a family and kids that carry the disease. After birth, a blood test can be done to find out if someone has a faulty gene that can develop into HD.

There is no cure for Huntington’s disease, or any treatment that can slow down the progress. However, physical and speech therapies can help the people with HD lead more normal lives. Medications are also given by doctors to help control emotions and ease feelings of depression. Recently, pharmaceutical companies like NeuroSearch have been searching and developing for a drug for the disease. They are trying to develop on Huntexil (pridopine) to make it into a regulator to control the central nervous system. Another technique that is tried is the use of transplants of brain cells; it appears to repair the damaged area of the brain caused by Huntington’s disease. Sherman Chen 3B

Works Cited:

Genetic Science Learning Center. "Huntington's Disease." Learn.Genetics 8 March 2011

National Institute of Neurological Disorders and Stroke. "Huntington's Disease Information Page."

National Institute of Neurological Disorders and Stroke (NINDS). Web. 08 Mar. 2011.

Hicks, Rob, and Trisha Macnair. "Huntington's Disease." BBC - Health: Huntington's Disease. Web. 09

Mar. 2011. .

Robinson, Richard. "Huntington's disease." The Gale Encyclopedia of Medicine. Detroit: Gale, 1999.

1489. Gale Science In Context. Web. 8 Mar. 2011. Sherman Chen 3B "Neurosearch pushes on with Huntington's disease drug." BioWorld Week 10 Jan. 2011: 3. Gale

Science In Context. Web. 8 Mar. 2011. (Recent Science Article that outlines new/upcoming information about the treatment or prevention of the Disease/Trait)

Pictures:

University of Utah. HD affects Basal Ganglia. Digital image. Huntington's Disease. Web. 8 Mar. 2011.

University of Utah. Mutation in chromosome 4. Digital image. Huntington's Disease. Web. 8 Mar. 2011.

Wikipedia. Pedigree showing how Huntington's disease is passed on. Digital image. Huntington's

Disease. Web. 8 Mar. 2011.