American baseball player Lou Gehrig (pictured) was diagnosed with amyotrophic lateral sclerosis, now commonly known in the United States as "Lou Gehrig's disease".

Henry Louis Gehrig, also known as Heinrich Ludwig Gehrig, was an American professional baseball first baseman who played 17 seasons in Major League Baseball (MLB) for the New York Yankees (1923–1939). Gehrig was renowned for his prowess as a hitter and for his durability, which earned him the nickname "the Iron Horse", and he is regarded as one of the greatest baseball players of all time. Gehrig was an All-Star seven consecutive times, a Triple Crown winner once, an American League (AL) Most Valuable Player twice and a member of six World Series champion teams. He had a career .340 batting average, .632 slugging average, and a .447 on-base average. He hit 493 home runs and had 1,995 runs batted in (RBIs). He is also one of 20 players to hit four home runs in a single game. In 1939, Gehrig was elected to the Baseball Hall of Fame and was the first MLB player to have his uniform number retired by a team when his number 4 was retired by the Yankees.

Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States and Canada—Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the broader group of motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and, lastly, breathe are all lost. While only 15% of people with ALS also fully develop frontotemporal dementia, an estimated 50% face at least some minor difficulties with thinking and behavior. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset or bulbar-onset.