What is ALS, the disease that killed actor Eric Dane?

Eric Dane, known for his roles on "Grey's Anatomy" and "Euphoria," died this week from amyotrophic lateral sclerosis at age 53.

The fatal nervous system disease, also known as Lou Gehrig's disease, killed Dane less than a year after he announced his diagnosis.

According to the Centers for Disease Control and Prevention, ALS is rare. In 2022, there were nearly 33,000 estimated cases, say researchers, who project that cases will rise to more than 36,000 by 2030.

WATCH: Former NYC deputy mayor raises millions for ALS research while facing his own mortality

The disease is slightly more common in men than in women and tends to strike in midlife, between the ages of 40 and 60.

Here's what to know.

What is ALS?

It affects nerve cells in the brain and spinal cord, causing loss of muscle control and getting worse over time.

ALS causes nerve cells in the upper and lower parts of the body to stop working and die. Nerves no longer trigger specific muscles, eventually leading to paralysis. People with ALS may develop problems with mobility, speaking, swallowing and breathing.

READ MORE: How did Stephen Hawking live 55 years with ALS?

The exact cause of the disease is unknown, and Mayo Clinic experts said a small number of cases are inherited.

It's called Lou Gehrig's disease after the Hall of Fame New York Yankees player. Gehrig was diagnosed with ALS in 1939 on his 36th birthday, died in 1941 and was the face of ALS for decades.

What are some signs of ALS?

Experts say the first symptoms are often subtle. The disease may begin with muscle twitching and weakness in an arm or leg.

Over time, muscles stop acting and reacting correctly, said experts at University of California San Francisco Health. People may lose strength and coordination in their arms and legs; feet and ankles may become weak; and muscles in the arms, shoulders and tongue may cramp or twitch. Swallowing and speaking may become difficult and fatigue may set in.

READ MORE: Did Lou Gehrig actually die of 'Lou Gehrig's disease'?

The ability to think, see, hear, smell, taste and touch are usually not affected, UCSF experts said.

Eventually, muscles used for breathing may become paralyzed. Patients may be unable to swallow and inhale food or saliva. Most people with ALS die of respiratory failure.

How is ALS diagnosed and treated?

The disease is difficult to diagnose because there's no test or procedure to confirm it. Generally, doctors will perform a physical exam, lab tests and imaging of the brain and spinal cord.

A doctor may interpret certain things as signs of ALS, including an unusual flexing of the toes, diminished fine motor coordination, painful muscle cramps, twitching and spasticity, a type of stiffness causing jerky movements.

READ MORE: FDA panel backs much-debated ALS drug in rare turnaround

There's no known cure for ALS, but the drug riluzole has been approved for treatment. According to the Mayo Clinic, it may extend survival in the early stages of the disease or extend the time until a breathing tube is needed.

Another much-debated drug, Relyvrio, was pulled from the U.S. market by Amylyx Pharmaceuticals in 2024. Its development had been financed, in part, by the ALS Association, the major beneficiary of the 2014 " ice bucket challenge " viral phenomenon.

Other medications are sometimes prescribed to help control symptoms.

Choking is common as ALS progresses, so patients may need feeding tubes. People may also use braces, wheelchairs, speech synthesizers or computer-based communication systems.

After the onset of the disease, experts say patients may survive from two years to a decade. Most people live from two to five years after symptoms develop, and about a fifth live more than five years after they are diagnosed.