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Friedreich's Ataxia
Friedreich's ataxia is a rare, inherited movement disorder
due to spinal cord damage.
WHAT ARE THE SIGNS OF FRIEDREICH'S ATAXIA?
As the name suggests, one of the signs of Friedreich's
ataxia is ataxia. Ataxia is an impairment in coordinating
movement. At first, the person may have difficulty
coordinating movements with the arms and performing
simple tasks such as writing or using utensils. Clumsy
hand movements are usually present.
A child with ataxia.
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There is a significant impairment in coordinating and controlling movement of the lower
extremities, which extends to the upper extremities. Friedreich's ataxia is also
characterized by muscle weakness. People with Friedreich's ataxia have a highly arched
foot or an exaggeration of the normal arch of the foot. This defect leads to a distinctive
impairment in walking in which the person appears unsteady. Scoliosis is usually present
in Friedreich's ataxia. Scoliosis is usually present in Friedreich's ataxia. Scoliosis is an
abnormal sideways curving of the bones that make up the structure surrounding the spinal
cord. 80 to 90% of patients have scoliosis of the thoracic spine (also known as T1
through T12). T1 through T12 refers to the twelve vertebrae (bones that form an opening
in which the spinal cord passes) that are behind an area of the body known as the thorax,
which is another name for chest.
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Another sign of Friedreich's ataxia is dysarthria. Dysarthria is a
difficulty in speech articulation that results from an impaired ability
to control the muscles involved in speech. The speech may sound
slurred. Rapid, involuntary eye movements may be present.
Tremors of the head may also be present, as may rapid heartbeat
and heart failure.
A positive Babinski's sign is present in Friedreich's ataxia. The
Babinski sign is an abnormal movement (except in newborns,
where it is normal) in which the big toe moves back and the other
toes fan out after stroking the side part of the bottom of the foot.
The presence of the Babinski reflex indicates damage to the pathway that connects the brain to the spine.
Romberg's sign may also be present. Romberg's sign is when a person loses balance when standing up
straight with their feet together and eyes closed. The presence of Romberg's sign indicates a loss of
position sense.
Reflexes are absent or decreased in Friedreich's ataxia. Friedreich's ataxia is followed by paralysis
(especially in the legs) and shortening of the muscles. Paralysis is loss of movement and/or sensation.
The signs of Friedreich's ataxia usually continue to get worse. Severe disability can result from this
condition.
WHEN DO THE SIGNS OF FRIEDREICH'S ATAXIA FIRST APPEAR?
The signs of Friedreich's ataxia usually first appear between the ages of 5 and 20. The most likely time for
the signs of Friedreich's ataxia to appear are at puberty. Puberty is the period of life in which the ability to
reproduce begins, which usually begins between the ages of 11 and 13.
HOW MANY PEOPLE DEVELOP FRIEDREICH'S ATAXIA?
Friedreich's ataxia affects 2 out every 100,000 people.
WHAT CAUSES FRIEDREICH'S ATAXIA?
Friedreich's ataxia is due to hardening of the side and back columns (pathways) of the spinal cord. The
back columns of the spinal cord are significantly hardened. Columns that travel from the brain to the spine
and from the spine to the cerebellum may be affected. The cerebellum is an area in the back, bottom part
of the brain that plays an important role in movement and coordination. Nerve impulses travel along these
columns so that different parts of the body can communicate.
Picture the columns as a road that cars travel on. If the columns become hardened this makes it difficult
for the nerve impulses to travel. It is much like how it is difficult to travel on a road that is not maintained
as opposed to one that is smoothly paved.
Friedreich's ataxia is transmitted to a child from a parent's genes. Genes are units of material contained in
a person's cells that contain coded instructions as for how certain bodily characteristics (such as eye
color) will develop. All of a person's genes come from his/her parents. There are many different forms of
genes. Some genes are normal whereas others may be abnormal. Abnormal genes can cause diseases,
as is the case in Friedreich's ataxia.
Genes are contained in structures called chromosomes. Each person has 23 pairs of chromosomes,
meaning that there are 46 chromosomes in total. One of each pair of chromosomes is inherited from the
mother and one of each pair is inherited from the father. The first 22 pairs of chromosomes (known as
autosomes) are not involved in determining sex. The 23rd pair of chromosomes, however, is involved in
determining sex.
Genes can either be dominant or recessive. A gene that masks the effect of another gene is called a
dominant gene. The gene whose expression is masked is known as a recessive gene. Nearly all cases of
Friedreich's ataxia is caused by recessive genes. Two defective recessive genes need to be present
(one from the mother and one from the father) for Friedreich's ataxia to develop. In chromosome pairs 1
through 22, recessive genes will only express themselves if one is present in the mother and the father.
When this happens, it is known as autosomal recessive inheritance.
A small percentage of cases of Friedreich's ataxia appear to be caused by a specific type of defective
dominant gene. Only one specific type of defective dominant gene needs to be present for this condition
to develop. If the defective gene is located on chromosomes 1 to 22, this type of inheritance is known as
autosomal dominant inheritance.
Chromosomes can be divided into different parts such as part a, part b, etc. The gene that causes
Friedreich's ataxia is located on part q of the 9th chromosome (abbreviated 9q). The gene is known as the
Friedreich's ataxia gene (abbreviated as FRDA). Genes contain substances known as nucleotides, which
are building blocks that contain the code for how certain proteins are produced. The nucleotides are
assembled in a specific order based on the type of protein that needs to be produced. It is much like how
the letters of a word (such as "b-o-o-k") need to be put in the correct order so that the word "book" is
spelled correctly.
To make proteins, the sequences of nucleotides sometimes need to be repeated a certain number of
times. There is a specific group of nucleotides (known as GAA) that are normally supposed to be repeated
7 to 22 times. In Friedreich's ataxia, these nucleotides repeat 800 to 1000 times. This type of repetitive
abnormality is known as a triplet repeat expansion. When an abnormality like this happens in the
production of proteins, it alters them, which can have devastating consequences to the body, one of
which is Friedreich's ataxia. The protein that is altered in Friedreich's ataxia is called frataxin.
The genetic defect in Friedreich's ataxia results in reduced levels of frataxin in the body. Without normal
levels of frataxin, certain cells in the body (such as those in the brain, spine, and muscles) cannot handle
normal levels of stress produced by the energy producing power-plants (known as mitochondria) inside of
cells. Research suggests that low levels of frataxin can lead to a buildup of iron inside the energy
producing power plants of cells. When the extra iron reacts with oxygen, it causes the production of
substances known as free radicals that can destroy cells and harm the body.
HOW IS FRIEDREICH'S ATAXIA TREATED?
Unfortunately, there is no cure for Friedreich's ataxia. Supportive braces may be used to prevent
deformities from developing and to make it easier to walk. Correcting the deformity of the arch of the foot
can help the patient retain the ability to walk for as long as possible. Such correction is usually only
performed if the signs of the condition do not seem to be progressing. Fusing parts of the bones together
that surround the spine may help correct the abnormal curving of the spine that is associated with this
condition.
Some promising developments occurred in December 2005, as a woman in the Netherlands was the first
to undergo stem cell treatment for Friedreich’s ataxia. Stem cells are cells that have the ability to divide
indefinitely and turn into a number of different specialized cells. In fact, stem cells eventually develop into
every type of tissue and organ in the human body. Stem cells are mostly found in the bone marrow. Bone
marrow is a type of tissue that fills the inside of bones.
In the case cited above, stem cells were taken from the umbilical cord of full-term babies and injected into
the patient’s blood and the bottom of her skull. The surgery was private and not available in the U.S. at
this time. Results of the treatment are unknown at this time.
WHAT IS THE PROGNOSIS FOR FRIEDREICH'S ATAXIA?
Prognosis for Friedreich's ataxia is poor. The signs generally get worse and can result in severe disability.
Within 10 years after signs have begun, more than half of people with this condition are confined to
wheelchairs. As was mentioned earlier, heart disease can occur. In cases where this occurs, death is
usually due to heart failure.
WHAT ELSE IS FRIEDREICH'S ATAXIA KNOWN AS?
Friedreich's ataxia is also known as hereditary spinal ataxia and heredotaxia.
WHAT IS THE ORIGIN OF THE TERM, FRIEDREICH'S ATAXIA?
Friedreich's ataxia is named Friedreich's ataxia after Nickolaus Friedreich, a German physician who lived
from 1825 to 1882.
