Huntington's disease(HD) is a hereditary brain disease which disrupts thinking, mood, behavior, and movement. It is named after Dr. George Huntington, who first described the disorder in his essay 'On Chorea' in 1872. Huntington's disease(HD) occurs in all regions of the world and in all ethnic populations. His description contains all the essential features considered disgnostic of Huntington’s Disease(HD): a progressive disorders combining chorea with behavioral disturbances and 'dementia', transmitted via an 'autosomal dominant' inheritance pattern. Huntington’s disease is the prototypic neurogenetic disorder, one of the first to be mapped(1983) and subsequently cloned(1993), and the model on which presymptomatic genetic testing is based.
♣ Chorea
☞ Uncontrolled movement, or tics, may develop in the fingers, feet, face, or trunk
☞ Clumsiness
☞ Jaw clenching (bruxism)
☞ Loss of coordination and balance
☞ Slurred speech
☞ Swallowing and/or eating difficulty
☞ Uncontrolled continual muscular contractions (dystonia)
☞ Walking difficulty, stumbling, falling
♣ Injury of Cognitive Functions
☞ Over time judgment, memory, and other cognitive
functions begin to deteriorate into dementia.
☞ The ability to concentrate becomes more difficult(Driving,
Keeping track of things, Making decisions, Answering questions, and may lose
the ability to recognize familiar objects).
♣ Psychiatric
Symptoms
☞ Depression(Hostility/irritability, Inability to take
pleasure in life 'anhedonia', Lack of energy)
☞ Bipolar disorder(Manic-depression) ☞ Delusions
☞ Hallucinations
☞ Inappropriate behavior(e.g., unprovoked aggression)
☞ Paranoia
☞ Behavioral changes
☞ Difficulty learning new things
☞ Speech difficulties
♣ Complications
☞ Constipation
☞ Incontinence of urine
☞ Weight loss
☞ Social isolation
Chorea
consists of involuntary, continuous, abrupt, rapid, brief, irregular movements
that flow randomly from one body part to another. The term derives from the
Latin word for a 'dance', but chorea is patternless, unlike most forms of
dance. Patients can partially and temporarily suppress choreic movements and
frequently 'camouflage' some muscle jerks by incorporating them into purposeful
activities. Chorea may be disabling because it interferes with voluntary
movements, resulting in clumsiness, speech and swallowing difficulty, and loss
of balance. Although chorea is the clinical hallmark of HD, other movement
problems, such as dystonia (more sustained muscle contractions resulting in
abnormal postures), myoclonus(very rapid jerk-like movements), rigidity(muscle
stiffness), bradykinesia(slowness of movement) often co-exist.
Cognitive
decline and various psychiatric symptoms may precede the motor manifestations
of HD. The neurobehavioral symptoms typically consist of personality changes,
apathy, social withdrawal, anxiety, impulsiveness, depression, mania, paranoia,
delusions, hostility, sleep disturbances, hallucinations, or psychosis.
Cognitive changes, manifested chiefly by loss of short-term memory, poor
judgment, and impaired concentration, occur in nearly all patients with HD;
however, some patients with late-onset chorea never develop dementia.
Huntington's
disease progresses without remission over 10 to 25 years and patients
ultimately are unable to care for themselves. Huntington's disease usually
appears in middle age(30~50 years), but can develop in younger and older
people.
Juvenile
HD(also called Westphal variant or akinetic-rigid HD) develops before the age
of 20, progresses rapidly, and produces muscle rigidity in which the patient
moves little, if at all(akinesia).
In
autosomal dominant inherited disease, a single abnormal allele is inherited
from one parent. Alleles are the pairs of genes that determine individual
characteristics. Any child, male or female, with one affected parent has a 50%
chance of inheriting Huntington's disease. Unaffected children of parent with
Huntington's cannot transmit the disease to their children because they have
not inherited the abnormal gene.
Experts
estimate that one in every 10,000 persons (nearly 30,000 in the United States)
have Huntington's disease. Juvenile Huntington's occurs in approximately 16% of
all cases. Huntington's disease is not prevalent within any particular
population. All races and ethnic groups, and both sexes are affected.
In
the United States, HD affects about 2 to 10 per 100,000 people, but in certain
regions of the world, like Lake Maracaibo, Venezuela and Moray Firth, Scotland,
the prevalence is much higher. Both men and woman may inherit the gene that
causes HD. HD usually begins in adulthood but may arise in children.
▣ Synonyms
☞ Huntington’s Disease(HD)
☞ Huntington’s Chorea☞ Hereditary Chronic Progressive Chorea
☞ Very Early Onset Huntington’s Disease(VEOHD)
☞ Chronic Progressive Chorea
☞ Degenerative Chorea
☞ Hereditary Chorea
☞ Woody Guthries Disease
