Causes. In 5 to 10 percent of cases, Lou Gehrig’s disease is inherited through a parent. The remaining 90 to 95 percent of cases, unfortunately, have no known cause. Doctors and researchers have identified several possible causes, such as gene mutation, chemical imbalance, mishandled proteins in the nerve cells, and/or erroneous immune system response. Certain risk factors, such as age (those over 40), sex (more men than women), and environmental factors (such as smoking, exposure to toxins, and history of viruses) also increase a person’s risk of developing the disease.
