What Is ALS?

ALS, amyotrophic lateral sclerosis or Lou Gehrig’s disease, is a progressive disease affecting the nerve cells resulting in a loss of muscle control. ALS causes motor neurons to gradually die. The neurons go from the brain to the spinal cord and then to the muscles. Motor neurons direct all muscle movements by transmitting messages from the spinal cord to muscles, so when they begin to die out and break down, the ability of the brain and spinal cord to communicate with muscles and direct their movement gradually breaks down. The ultimate result is some muscles becoming paralyzed while others are severely weakened.

The exact cause of ALS and why ALS affects some people but not others is unknown. It is believed to be caused by both environmental and genetic factors. Environmental factors such as exposure to pollutants and working with silica are thought to increase one’s likelihood of developing ALS. It is important to note that relatively little is known about the connection between ALS and these environmental factors, but they are thought to increase the risk of ALS. There are also genetic factors likely at play. For example, 30-40% of familial ALS in the U.S. and Europe is caused by a mutation in the C9orf72 gene. This gene provides instructions for making proteins which are abundant in nerve cells including motor neurons and helps regulate cellular trafficking, the distribution of macromolecules throughout the cell. The loss of function of this gene has been found to make motor neurons more susceptible to other damages, possibly leading to the neurodegeneration characteristic of ALS.