Alan Jackson has Charcot-Marie-Tooth disease (CMT) , a hereditary nerve disorder that affects balance, coordination, and muscle strength.

What it is

CMT is a neurological condition that can gradually make walking and performing more difficult, which is why Jackson has talked about trouble with balance onstage.

Why it matters

He has said the condition has affected him for years and was a major reason he stepped back from touring.

In plain terms

It’s not usually described as a terminal illness, but it is a long-term, progressive nerve disease that can seriously affect mobility.