The official name of the illness is amyotrophic lateral sclerosis (ALS), but in the U.S. it is better known as Lou Gehrig’s disease. The great New York Yankees first baseman was diagnosed with ALS in 1939 and died two years later from the progressive neuromuscular disorder, which attacks nerve cells that lead from the brain and the spinal cord to muscles throughout the body. When these motor neurons die, the brain can no longer control muscle movements; in the later stages of the disease, patients become totally paralyzed.

First described in 1869 by French clinician Jean-Martin Charcot, ALS is a misunderstood illness. Doctors once thought it was rare but now consider it fairly common: about 5,000 people in the U.S. are diagnosed with ALS every year. In total there are about 30,000 ALS patients in the U.S. and approximately 5,000 in the U.K. ALS typically develops between the ages of 40 and 70, but the disease strikes younger and older patients as well. Other well-known people who suffered from ALS include British actor David Niven, Russian composer Dmitri Shostakovich and Chinese leader Mao Tse-tung. Researchers have found unusual clusters of patients with the disorder among Italian soccer players, veterans of the Persian Gulf War and residents of the island of Guam, although no one knows why.