Amyotrophic Lateral Sclerosis (ALS)
ALS is the group name for certain degenerative neuromuscular diseases. Degenerative means it progressively gets worse over time. Neuromuscular means it involves both the nervous system and the muscular system. In the case of ALS, motor neurons gradually deteriorate and die. As a result, muscles gradually weaken, twitch, and atrophy. Eventually the brain loses the ability to initiate and control voluntary movements.
The Centers for Disease Control and Prevention estimate for In 2016 the Centers for Disease Control and Prevention estimated that between 14,000 - 15,000 Americans have ALS. ALS is a common neuromuscular disease worldwide. It affects people of all races and ethnic backgrounds.
There are several potential risk factors for ALS including:
Age. Although the disease can strike at any age, symptoms most commonly develop between the ages of 55 and 75. Gender. Men are slightly more likely than women to develop ALS. However, as we age the difference between men and women disappears. Race and ethnicity. Most likely to develop the disease are Caucasians and non-Hispanics. Some studies suggest that military veterans are about 1.5 to 2 times more likely to develop ALS. Although the reason for this is unclear, possible risk factors for veterans include exposure to lead, pesticides, and other environmental toxins. ALS is recognized as a service-connected disease by the U.S. Department of Veterans Affairs.
Sporadic ALS The majority of ALS cases (90 percent or more) are considered sporadic. This means the disease seems to occur at random with no clearly associated risk factors and no family history of the disease. Although family members of people with sporadic ALS are at an increased risk for the disease, the overall risk is very low and most will not develop ALS.
Familial (Genetic) ALS About 5 to 10 percent of all ALS cases are familial, which means that an individual inherits the disease from his or her parents. The familial form of ALS usually only requires one parent to carry the gene responsible for the disease. Mutations in more than a dozen genes have been found to cause familial ALS. About 25 to 40 percent of all familial cases (and a small percentage of sporadic cases) are caused by a defect in a gene known as “chromosome 9 open reading frame 72,” or C9ORF72. Interestingly, the same mutation can be associated with atrophy of frontal-temporal lobes of the brain causing frontal-temporal lobe dementia. Some individuals carrying this mutation may show signs of both motor neuron and dementia symptoms (ALS-FTD). Another 12 to 20 percent of familial cases result from mutations in the gene that provides instructions for the production of the enzyme copper-zinc superoxide dismutase 1 (SOD1).