Country music star Alan Jackson has announced his farewell tour, “Last Call: One More for the Road,” and has promised to “give [fans] the best show I can,” Billboard reports. The Grammy-winning musician went public about living — and performing — with a neurological condition called Charcot-Marie-Tooth disease in 2021, about a decade after being diagnosed. “There’s no cure for it, but it’s been affecting me for years. And it’s getting more and more obvious,” Jackson told Today.

Here’s what to know about Charcot-Marie-Tooth disease, or CMT, and how it can affect those who, like Jackson, have it.

What is CMT?

Charcot-Marie-Tooth disease is a genetic neurological condition that causes damage to the peripheral nerves that connect the spine and brain to the arms and legs, according to the Mayo Clinic. “It’s genetic, I inherited from my daddy,” Jackson explained during his 2021 Today appearance. CMT is one of the most common inherited neurological conditions and affects about 1 in every 2,500 people in the U.S., according to the Hereditary Neuropathy Foundation.

The nerve damage from CMT can result in muscle shrinkage and weakness, especially in the ankles and feet. Some patients eventually develop hand weakness too, although it’s less common, Dr. John Kincaid, a neurologist at Indiana University School of Medicine, who specializes in the disease, tells Yahoo Life. Although some nerve damage, or neuropathy, can cause pain or loss of sensation, these issues are “very secondary” to muscle weakness in CMT, and most people don’t experience them.

How do people develop CMT?

The condition is inherited, so people are born with one or more genetic mutations that cause CMT. But symptoms may not appear until someone is in their 20s. Some patients don’t know they have the disease until they’re in their 50s, Kincaid says. Others might start having symptoms during their teenage years.

What are the symptoms?

Weakness is the most common symptom of CMT. Specifically, signs of ankle weakness and instability tend to emerge first, along with weakness in the feet and legs. Someone with CMT might notice the symptoms while they are “standing still, in a crowd or in a checkout line, where the person has to maintain balance without holding onto something,” Kincaid says. Or they might trip easily and have “trouble with curbs,” he adds. Doctors diagnose the disease with electromyography to measure the activity of the muscles and nerves that control them. This is often followed by a genetic test.

One early potential warning sign is an “abnormally high arched foot,” Kincaid explains. A doctor might suspect the disease if a teenager is having ankle weakness and both the adolescent and one of the teen’s parents have the same unusually high arch. But to be clear, “not every high-arched foot is due to CMT” and a high arch doesn’t occur in all patients who do have the disease, he says.

Some people with CMT might have some loss of sensation in their hands, feet and legs, but “most patients do not have a major pain component,” says Kincaid. “No burning, fiery feet prickles, tingles or numbness.”

Does it get worse with age?

CMT does tend to progress with age. But it typically moves slowly, according to Kincaid. Most people will develop mobility impairments, such as unsteadiness when standing, he says, but it may be 10 to 30 years after onset that they’ll need assistive devices, such as ankle braces, canes or rollators, also known as walkers.

Jackson has said little about his particular symptoms. But some patients do develop hand weakness, for which there aren’t many assistive devices, Kincaid notes. If the disease were to affect Jackson’s hands, “it’s likely he might have some trouble with his guitar playing, fingering frets and plucking strings,” explains Kincaid. Even if the CMT weakness is isolated to Jackson’s ankles and feet, however, “just standing on stage and walking onstage — those could be big problems,” he says.

On the bright side, Kincaid points out it’s very rare that CMT patients lose enough mobility to need wheelchairs; for most, ankle braces or perhaps a cane provide enough support.

Are there treatments?

There’s currently no cure and no treatment for the genetic disease. “But the research pipeline suggests that we soon will have a potential, true genetic treatment” — meaning, a gene therapy to fix the mutation that causes CMT — “for the most common type,” says Kincaid.