2. Definition
Huntington's disease (HD) is a neurodegenerative genetic disorder
characterized by the gradual onset of defects in behavior, cognition, and
movement beginning in the fourth and fifth decades of life, with an
average life expectancy of about 10-20 years thereafter.
The worldwide prevalence of HD is 5–10 cases per 100,000 persons.
The hallmark of the disease is a movement
disorder consisting of rapid, jerky motions with
no clear purpose, which is why the disease used
to be called Huntington's chorea; these
choreiform movements may be confined to a
finger or may involve a whole extremity, the
facial musculature, or even the vocal apparatus.
HD usually presents as an alternation in mood
(especially depression) or a change in
personality. Defects of memory and attention
may also occur.
A profound but selective atrophy of the caudate
and putamen is associated with these clinical
manifestations. (see the photo on the right)
3. Genetic Basis
The mutation of Huntingtin is an unstable CAG (cytosine-adenine-guanine)
triplet repeat. In normal individuals, Huntingtin contains between 15 and 34
repeats, whereas the gene in HD patients contains from 42 to 66 repeats.
Huntington's disease is
inherited in an autosomal
dominant pattern. If one of your
parents has Huntington's
disease, you have a 50 percent
chance of getting it.
Why this dominant disorder
endured the evolutionary
selection? Because its
symptoms usually do not
appear until age 35 or later,
after the person has passed on
the dominant allele to his or her
children.
5. Opinion & Treatment
A blood test can tell you if have the HD gene and will
develop the disease. Genetic counseling can help you weigh
the risks and benefits of taking the test.
There is no cure. Medicines can help manage some of the
symptoms, but cannot slow down or stop the disease
6. References
Neuroscience 3rd edition, by Dale Purves et al
Child Development 8th edition, by Laura E. Berk
http://dailydiseasesanddisorders.tumblr.com/post/60401
94582/huntingtons-disease
http://www.studyblue.com/notes/note/n/2-3-
13/deck/5374356
http://www.eurostemcell.org/factsheet/huntington%E2%
80%99s-disease-how-could-stem-cells-help
http://en.wikipedia.org/wiki/Huntington%27s_disease#R
esearch_directions