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Huntington's Disease: Hope Through Research
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Huntington's Disease: Hope Through Research
National Institute of Neurological Disorders and Stroke
(NINDS 1998) |
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Glossary
- akinesia: impaired body movement.
- at-risk: a description of a person whose mother or father
has HD or has inherited the HD gene and who therefore has a 50-50
chance of inheriting the disorder.
- autosomal dominant disorder: a non-sex-linked
disorder that can be inherited even if only one parent passes
on the defective gene.
- basal ganglia: a region located at the base of
the brain composed of four clusters of neurons, or nerve cells.
This area is responsible for body movement and coordination. The
neuron groups most prominently and consistently affected by HD--the
pallidum and striatum--are located here. See neuron, pallidum,
striatum.
- caudate nuclei: part of the striatum in the basal
ganglia. See basal ganglia, striatum.
chorea: uncontrolled body movements. Chorea is derived
from the Greek word for dance.
- chromosomes: the structures in cells that contain
genes. They are composed of deoxyribonucleic acid (DNA) and proteins
and, under a microscope, appear as rod-like structures. See deoxyribonucleic
acid (DNA), gene.
- computed tomography (CT): a technique used for
diagnosing brain disorders. CT uses a computer to produce a high-quality
image of brain structures. These images are called CT scans.
cortex—part of the brain responsible for thought, perception,
and memory. HD affects the basal ganglia and cortex. See basal
ganglia.
- deoxyribonucleic acid (DNA): the substance of
heredity containing the genetic information necessary for cells
to divide and produce proteins. DNA carries the code for every
inherited characteristic of an organism. See gene.
dominant—a trait that is apparent even when the gene for
that disorder is inherited from only one parent. See autosomal
dominant disorder, recessive, gene.
- gene: the basic unit of heredity, composed of
a segment of DNA containing the code for a specific trait. See
deoxyribonucleic acid (DNA).
- huntingtin: the protein encoded by the gene that
carries the HD defect. The repeated CAG sequence in the gene causes
an abnormal form of huntingtin to be formed. The function of the
normal form of huntingtin is not yet known.
- kindred: a group of related persons, such as a
family or clan.
magnetic resonance imaging (MRI)—an imaging technique that
uses radiowaves, magnetic fields, and computer analysis to create
a picture of body tissues and structures.
- marker: a piece of DNA that lies on the chromosome
so close to a gene that the two are inherited together. Like a
signpost, markers are used during genetic testing and research
to locate the nearby presence of a gene. See chromosome, deoxyribonucleic
acid (DNA).
- mitochondria: microscopic, energy-producing bodies
within cells that are the cells’ "power plants."
- mutation: in genetics, any defect in a gene. See
gene.
- myoclonus: a condition in which muscles or portions
of muscles contract abnormally.
- neuron: a nerve cell, the basic impulse-conducting
unit of the nervous system. Nerve cells communicate with other
cells through an electrochemical process called neurotransmission.
neurotransmitters—special chemicals that transmit nerve impulses
from one cell to another.
- pallidum: part of the basal ganglia of the brain.
The pallidum is composed of the globus pallidus and the ventral
pallidum. See basal ganglia.
- positron emission tomography (PET): a tool used
to diagnose brain functions and disorders. PET produces three-dimensional,
colored images of chemicals or substances functioning within the
body. These images are called PET scans.
- prevalence: the number of cases of a disease that
are present in a particular population at a given time.
- putamen: an area of the brain that decreases in
size as a result of the damage produced by HD.
- receptor: recognition sites on cells that cause a response
in the body when stimulated by certain chemicals called neurotransmitters.
They act as on-and-off switches for the next nerve cell. See neuron,
neurotransmitters.
- recessive: a trait that is apparent only when
the gene or genes for it are inherited from both parents. See
dominant, gene.
senile chorea—a relatively mild and rare disorder found in
elderly adults and characterized by choreic movements. It is believed
by some scientists to be caused by a different gene mutation than
that causing HD.
- striatum: part of the basal ganglia of the brain.
The striatum is composed of the caudate nucleus, putamen, and
ventral striatum. See basal ganglia, caudate nuclei.
- trait: any genetically determined characteristic.
See dominant, gene, recessive.
- transgenic mice: mice that receive injections
of foreign genes during the embryonic stage of development. Their
cells then follow the "instructions" of the foreign
genes, resulting in the development of a certain trait or characteristic.
Transgenic mice can serve as an animal model of a certain disease,
telling researchers how genes work in specific cells.
- ventricles: cavities within the brain that are
filled with cerebrospinal fluid. In HD, tissue loss causes enlargement
of the ventricles.
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