Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease).
When both two homozygous recessive SOD1 genes mutate and are inherited by two parental organisms, or when one dominate and one recessive SOD1 genes mutate, Amyotrophic Lateral Sclerosis (ALS) occurs. The SOD1 gene is part of the long arm (as opposed to the shorter arm) of chromosome 21. Mutations in genes on chromosome 21 play roles in one form of Alzheimer's disease, progressive myoclonus epilepsy, autoimmune poly glandular syndrome type I, and many other diseases. The vast majority of ALS cases are, in fact, not inherited, but caused by some unknown reason. Approximately, 10% of all ALS cases are caused by heredity, while the other 90% through speculated viral and environmental causes. .
The reason the SOD1 gene is important to this condition is because the enzyme coded for by SOD1 carries out a very important function in cells: it removes dangerous super oxide radicals by converting them into non-harmful materials. Defects in the action of this enzyme mean that the super oxide radicals attack cells from the inside, causing their death. Several different mutations in this enzyme all result in ALS, making the exact molecular cause of the disease difficult to determine. .
There are many symptoms/signs of this disease. In the early stages of ALS, tripping, dropping things, slurred or "thick" speck and muscle cramping, weakening, and twitching may occur. Some people think that these symptoms are normal signs of aging, and sometimes people don't go to the doctor before it is too late, though there is no definite cure. As the disease progresses, essential muscles are eaten away. An example as to how this is problematic is the weakness of the breathing muscles. They essential control breathing, and once they stop working, one cannot breathe. In some people, the muscles for speaking, swallowing or breathing are the firs to be affected. This is known as "Bulbar ALS".
