sed so successfully.It is said that Huntington’s disease was first introduced to Australia by a Somerset woman who arrived in Tasmania aboard the “Arab” ship in 1842. She had thirteen children; eight with her first husband and five with her second. Five of the six females and four of the seven males inherited the disease.Causes of the DisorderThis disease is genetically inherited and is a dominant characteristic, therefore unfortunately the offspring of a victim has 50% chance of inheriting the disease.The DNA contains four types base: A (adenine) and T (thymine), G (guanine) and C (cytosine). These four letters make up the genetic alphabet and they spell out the commands for every single cell and organ of the body and also determine all the characteristics of the person.In 1993 it was discovered that a segment of DNA on the arm of chromosome 4 is linked to the HD gene. They found that at one end of the HD gene, the combination CAG is repeated too many times. In people without HD this CAG is repeated 5 to 35 times. In people who are affected by HD, CAG is repeated over and over again between 36 and 121 times.The CAG combination codes for a protein called huntingtin. Why the increase number of CAG causes HD is still unknown. It is thought that too much of the HD protein makes them obtain some new, abnormal property. This is true in two other disorders caused by repeats of three letters, spinocerebeller ataxia type 1 and X-linked spinal and bulbar muscular atrophy. It may also be true in all CAG-related genetic diseases.The HD gene is present in almost every cell of the body. However, it only affects the brain. Moreover, the huntingtin protein is present in all parts of the brain but it only affects some parts. The region of the brain most affected by HD is the striatum. The nerve cells in the striatum are especially affected. It is unclear why the HD gene affects that particular part of the brain so badly...
