Myasthenia Gravis and Other Rare Diseases Difficult To Diagnose

Stephen Hawking’s rare neurodegenerative disease defined him almost as much as his physics. He used his celebrity to put the spotlight on muscle-wasting amyotrophic lateral sclerosis, posting videos of his family taking the ice-bucket challenge on his behalf to raise funds and awareness about a disease that often draws sympathy but rarely money for drug development and research.

The definition of what constitutes a rare disease varies widely, with the US defining it as a condition that affects fewer than 1 in 200,000, and the European Union using it to describe