Claim: Huntington's disease is sometimes caused by a permanent change in an organism's genetic elements.

Huntington 's disease -LRB- HD -RRB- , also known as Huntington 's chorea , is an inherited disorder that results in death of brain cells . The earliest symptoms are often subtle problems with mood or mental abilities . A general lack of coordination and an unsteady gait often follow . As the disease advances , uncoordinated , jerky body movements become more apparent . Physical abilities gradually worsen until coordinated movement becomes difficult and the person is unable to talk . Mental abilities generally decline into dementia . The specific symptoms vary somewhat between people . Symptoms usually begin between 30 and 50 years of age , but can start at any age . The disease may develop earlier in life in each successive generation . About 8 % of cases start before the age of 20 years and typically present with symptoms more similar to Parkinson 's disease . People with HD often underestimate the degree of their problems .   HD is typically inherited from a person 's parents , with 10 % of cases due to a new mutation . The disease is caused by an autosomal dominant mutation in either of an individual 's two copies of a gene called Huntingtin . This means a child of an affected person typically has a 50 % chance of inheriting the disease . The Huntingtin gene provides the genetic information for a protein that is also called `` huntingtin '' . Expansion of CAG -LRB- cytosine-adenine-guanine -RRB- triplet repeats in the gene coding for the Huntingtin protein results in an abnormal protein , which gradually damages cells in the brain , through mechanisms that are not fully understood . Diagnosis is by genetic testing , which can be carried out at any time , regardless of whether or not symptoms are present . This fact raises several ethical debates : the age at which an individual is considered mature enough to choose testing ; whether parents have the right to have their children tested ; and managing confidentiality and disclosure of test results .   There is no cure for HD . Full-time care is required in the later stages of the disease . Treatments can relieve some symptoms and in some improve quality of life . The best evidence for treatment of the movement problems is with tetrabenazine . HD affects about 4 to 15 in 100,000 people of European descent . It is rare among Japanese , while the occurrence rate in Africa is unknown . The disease affects men and women equally . Complications such as pneumonia , heart disease , and physical injury from falls reduce life expectancy . Suicide is the cause of death in about 9 % of cases . Death typically occurs fifteen to twenty years from when the disease was first detected .   The first likely description of the disease was in 1841 by Charles Oscar Waters . The condition was described in further detail in 1872 by George Huntington , after whom it is named . The genetic basis was discovered in 1993 by an international collaborative effort led by the Hereditary Disease Foundation . Research and support organizations began forming in the late 1960s to increase public awareness , to provide support for individuals and their families , and to promote research . Current research directions include determining the exact mechanism of the disease , improving animal models to aid with research , testing of medications to treat symptoms or slow the progression of the disease , and studying procedures such as stem cell therapy with the goal of repairing damage caused by the disease .