Which rare disease did Stephen Hawking have?

Stephen William Hawking (8 January 1942 – 14 March 2018) was an English theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge at the time of his death. He was the Lucasian Professor of Mathematics at the University of Cambridge between 1979 and 2009.

For decades, a legendary scientist was confined to a wheelchair by a form of amyotrophic lateral sclerosis, or Lou Gehrig’s Disease, a neurological disease that impacts movement. He communicated via a speech synthesizer.

ALS is short for amyotrophic lateral sclerosis, which is also known as Lou Gehrig's disease. ALS is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord, according to the ALS Association.