The information you are going to get from this Article are:
1. Introduction of Ataxia.
2. Anatomy of the Cerebellum.
3. Types of Ataxia.
A neurological disease that causes abnormal and uncontrolled movement of different parts of the body such as legs, hands, eyes, etc is called ataxia. It results when the cerebellum (a part of the brain that coordinates and adjusts the movements of the body). The condition of the ataxia patient worsens as the time passes. The life span of an Ataxia patient is also less compared to a normal person. Ataxia has many different types. Some of them are Cerebellar ataxia, Ataxia-telangiectasia, Friedreich’s ataxia, etc.
Anatomy of Cerebellum
The body’s nervous system consists of the brain and the spinal cord. The brain is the most complex organ that performs a vital role in the body. The brain not only controls the thoughts but also the physical activities of the body. The brain is divided into different parts that perform specific functions. The cerebellum (little brain) is among the main parts of the brain. It is present in the hindbrain, behind the brain stem, beneath the temporal and occipital lobes. The main function of the cerebellum is to detect errors in the movement of the body and correct them and also provide equilibrium. The main functional parts of the cerebellum are the cerebrocerebellum, spinocerebellum, and vestibulocerebellum. The inputs sent by the cerebral cortex are received by the cerebrocerebellum. The cerebrocerebellum is responsible for movement planning. The spinocerebellum performs its function by controlling the posture and maintaining the movement of the body. The vestibulocerebellum plays a vital role in maintaining the ocular reflexes (stabilization of the eye during head movement) and balancing the body movement.
Types of Ataxia
1. Ataxia Telangiectasia (AT)
A rare genetic disorder that affects multiple body systems and is caused by a mutation in the protein called Ataxia Telangiectasia Mutated serine-threonine kinase (ATM serine-threonine kinase). This protein normally fixes the damaged DNA and it is also important for the development of some immune cells such as T-lymphocytes. This type of ataxia occurs due to the autosomal recessive mutation in the gene of ATM. Due to this, the ATM protein is incapable to perform its function and repair the damaged DNA. Ataxia-telangiectasia could also cause some other chronic health conditions like lung infections, lymphoma (cancer of the immune system cells), leukemia (cancer of the blood-forming cells or tissues such as bone marrow), etc. Symptoms include difficulty in writing, and speaking, unsteady gait, spider veins or blood vessels that appear on the corner of the eyes, etc. This disorder can be characterized by genetic testing, a high level of Alpha-fetoprotein, a low level of immunoglobulin, etc. Ataxia-telangiectasia has no cure but symptoms can be treated. Your doctor may prescribe you some antibiotics and supplements of immunoglobulin, etc. Don’t take any medicine without asking your doctor.
2. Friedreich’s Ataxia (FRDA)
A type of ataxia that affects the GAA (guanine, adenine, adenine) sequence in the FXN gene (a gene that is present on chromosome 9). Normally, the FXN gene has a short number of GAA copies. But, in the FRDA there is an abnormal repetition of GAA sequences. That means there are hundreds of copies of GAA present.
• Normal FXN Gene Vs Mutated FXN Gene
n a normal condition, the FXN gene is used to encode a protein called Frataxin that is present in the mitochondria (an organelle that provides energy to the cell). The function of Frataxin is to make clusters of iron and sulfur. The iron-sulfur clusters are important for the transfer of electrons in the mitochondria. These electron transfers play an important part in mitochondrial ATP production. The patient with FRDA has a mutation in the FXN gene. Due to this, there is insufficient production of Frataxin protein. So, it becomes difficult for the mitochondria to produce the iron-sulfur clusters. This results in a low level of ATP production. This means, there is less energy production for cells.
• Inherited Disorder
FRDA is an inherited autosomal disorder. That means it is passed from parents to offspring. The carriers of FRDA have one mutated and one normal gene and usually show no symptoms. When both the parents are carriers they pass both the copies of affected genes to the offspring. As a result, the child will have ataxia.
• Oxidative Damage
FRDA causes the accumulation of iron in the mitochondria where the iron will react with oxygen forming free radicals. These free radicals damage the proteins and DNA of the cells. This process of damage is called oxidative damage. Due to less energy production, the cells that are dependent on the mitochondrial function start to damage. This cell damage ends up causing other health problems such as Diabetes mellitus, Hypertrophic cardiomyopathy, etc.
The symptoms of FRDA are difficulty in walking, tiredness, heart problems, loss of vision and hearing, etc. The diagnosis of FRDA includes genetic testing for checking if there is any mutation in the FXN gene, heart tests, MRI scans, etc. We have already discussed that there is no cure for ataxia but the symptoms may be treated.