Huntington’s disease An inherited, degenerative
disorder of structures in the BRAINthat regulate
movement, mood and personality, and cognitive
function and memory. Huntington’s disease fol-
lows an autosomal dominant INHERITANCE PATTERN,
with each child of an affected parent having a 50
percent chance of inheriting the GENE MUTATION
that allows the condition to develop. The defective
gene is IT-15 on CHROMOSOME4. It causes an alter-
ation in a protein called the Huntington protein
that has a key, though poorly understood, role in
maintaining the putamen and the caudate
nucleus, two structures within the basal ganglia.
All people have the Huntington protein; the pro-
tein’s function becomes defective when the gene
that regulates it is mutated. People who have the
mutation for Huntington’s disease will develop the
disorder, generally in midlife though occasionally
the disorder manifests in late ADOLESCENCE(juve-
nile Huntington’s disease).
Symptoms and Diagnostic Path
Early symptoms of Huntington’s disease are
general and may not appear related. They include
- irritability
- DEPRESSION, BIPOLAR DISORDER, or anxiety
- anger and hostility
- diminished energy
- disturbances of balance and coordination
- forgetfulness
- inability to concentrate
- delusions and hallucinations
As the disease progresses the neuromuscular
symptoms become more pronounced and include
DYSKINESIA(notably CHOREAand ATHETOSIS) and DYS-
TONIA. Cognitive dysfunction also becomes promi-
nent, and the person may no longer recognize
familiar places and people. PSYCHOSIS may also
increase.
The diagnostic path includes a comprehensive
medical examination, detailed exploration of PER-
SONAL HEALTH HISTORYand FAMILY MEDICAL PEDIGREE,
and NEUROLOGIC EXAMINATION. Diagnostic imaging
procedures such as COMPUTED TOMOGRAPHY (CT)
SCAN orMAGNETIC RESONANCE IMAGING (MRI) may
show changes in the brain characteristic of Hunt-
ington’s disease though these changes are not con-
clusively diagnostic. The only certain diagnostic
procedure is GENETIC TESTING, done from a sample
of BLOOD, to determine whether the IT-15 gene is
defective.Treatment Options and Outlook
Huntington’s disease is progressive and fatal, gen-
erally causing death 15 to 30 years after the onset
of symptoms. Treatment aims to improve symp-
toms and QUALITY OF LIFE. Treatment may include
ANTIPSYCHOTIC MEDICATIONS, ANTIDEPRESSANT MEDICA-
TIONS, ANTIANXIETY MEDICATIONS, and BOTULINUM
THERAPYto relieve dystonia. Therapeutic needs and
effectiveness changes as the disease progresses.
Emotional support through counseling and SUP-
PORT GROUPSis often helpful for the person who
has Huntington’s disease and for family members
and caregivers. Most people who develop Hunt-
ington’s disease can remain active and independ-
ent for 10 years or so after the onset of symptoms.Risk Factors and Preventive Measures
The only risk for Huntington’s disease is genetic.
As yet researchers do not know how to prevent
Huntington’s disease from developing in those
who carry the mutated gene. Genetic testing to
detect the presence of the gene in people who
have a family history of Huntington’s disease but
have no symptoms themselves is available; how-
ever, it is because there are no known treatments
for the disorder. Though finding the gene is nor-
mal is a great relief, learning one carries the
mutated gene is often a difficult challenge. Some
people prefer to know so they can make appropri-
ate plans and decisions, including family planning.
Health experts strongly recommend GENETIC COUN-
SELING for people who have family history of
Huntington’s disease or symptoms that suggest
Huntington’s disease.
See also COGNITIVE FUNCTION AND DYSFUNCTION;
DELUSION; END OF LIFE CONCERNS; HALLUCINATION;
MEMORY AND MEMORY IMPAIRMENT; PARKINSON’S DIS-
EASE.hydrocephaly Excessive cerebrospinal fluid
within the cranium (skull). Hydrocephaly, also
called hydrocephalus, may develop for numerous
reasons, such as congenital BRAINdefects, TRAU-256 The Nervous System