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Glossary of Terms

Huntington's Disease Center at Johns Hopkins
At-riskmeaning the patient has a parent or sibling who has tested positive for the Huntington's disease
(HD) gene.
Anticipationoccurs when a child develops a disease earlier than his or her parent.
CAG Repeatthe repeating unit of DNA ("triplet repeat") present in all normal huntington genges, which when expanded to 36 or more units ("mutant") causes HD.
Chorearefers to involuntary twitching movements that first tend to involve the fingers and toes and then progress to include the whole body
Dementiarefers to a gradual loss of intellectual abilities such as memory, concentration, problem solving, and judgment.
Dominantmeaning that one need only inherit the gene from one parent to get the disease.
Genetic testingwhen a person gives a blood sample so that he or she can be tested for the presence of a specific hereditary disease.
Hereditarymeaning that it is caused by a gene that is passed from parent to child.
Movement disorderThe movement disorder associated with HD consists of two parts: involuntary twitching movements (chorea) and difficulties with voluntary movements in the form of clumsiness, stiffness, or trouble with walking.
Neurodegenerativemeaning that it is a progressive condition, which results from accumulating damage to specific areas of the nervous system
Psychiatric disturbancesmeaning that the patient may develop depression, mania, irritability, apathy or personality changes.
Personality changeschanges in behavior or interactions with other people that so no not fall into another diagnostic category.
Presymptomaticwhen someone is carrying the abnormal ("mutant" or "expanded") gene, but does not yet have symptoms of the manifest disease.
Recessivemeaning that one must get the gene from both sides of the family to have the disease.
Symptomaticmeaning that a person is carrying the abnormal gene, and showing signs and symptoms of the disease.