A disorder that affects voluntary muscle movement, amyotrophic lateral sclerosis, or ALS, affects 20,000 people in the United States, according to the National Institute of Neurological Disorders and Stroke. Also called Lou Gehrig's disease, amyotrophic lateral sclerosis causes patients' muscles to weaken, resulting in muscle wasting and twitching. The MayoClinic.com points out that while amyotrophic lateral sclerosis cases that are not caused by genetics appear to be random, certain factors may cause the disease, though scientists are still studying their full effects.
Genetics
The MayoClinic.com notes that up to 10 percent of amyotrophic lateral sclerosis cases result from genetics. Doctors have identified four gene mutations that cause amyotrophic lateral sclerosis: ALS2, SETX, SOD1 and VAPB. Each gene mutation causes a different type of amyotrophic lateral sclerosis. For example, a mutation of the ALS2 gene, a gene involved in the production of the alsin protein, causes type 2 amyotrophic lateral sclerosis. The cause of type 4 amyotrophic lateral sclerosis, the mutation of the SETX gene, affects the production of the senataxin protein. A mutation of the VAPB gene, which results in type 8 amyotrophic lateral sclerosis, affects vesicles-associated membrane protein production. With type 1 amyotrophic lateral sclerosis, patients have a mutation of the SOD1 gene, which helps with the production of the superoxide dismutase protein. The mutation to the SOD1 gene also affects cells' protection from free radicals, which result from oxygen metabolism.
The inheritance pattern for amyotrophic lateral sclerosis depends on the type of mutated gene. The Genetics Home References explains that patients with amyotrophic lateral sclerosis caused by ALS2 need two copies of the gene, while patients with amyotrophic lateral sclerosis caused by SETX, SOD1 or VAPB only need one copy of the gene.
Glutamate
Another possible cause of amyotrophic lateral sclerosis is high levels of glutamate, a neurotransmitter in the brain. As a neurotransmitter, glutamate is involved in brain communication. Patients with amyotrophic lateral sclerosis have higher levels of glutamate in the spinal fluid and serum, which is part of the blood, compared to patients without the disorder. Too much glutamate is toxic for cells, resulting in cell death. The National Institute of Neurological Disorders and Stroke explains that scientists are working to understand why the buildup of glutamate occurs and how it contributes to the onset of amyotrophic lateral sclerosis.
Autoimmune Response
The MayoClinic.com notes that an abnormal autoimmune response may cause amyotrophic lateral sclerosis in some patients. In these cases, the patient's body produces antibodies that result in her immune system attacking normal cells instead of an invading virus as it normally would. This abnormal autoimmune response may interfere in the motor neurons' function, the cells affected by amyotrophic lateral sclerosis. For example, this autoimmune response may affect the motor neurons communication signals between the brain and body, thus resulting in the muscular problems.
