Celine Dion “doesn’t have control over her muscles”.

The My Heart Will Go On hitmaker cancelled her world tour in December 2022 after being diagnosed with stiff person syndrome, an uncurable neurological condition . And while her “goal” is to return to the stage one day, her sister, Claudette Dion, 74, suggested it seems unlikely at the moment.

Speaking to Canadian website 7 Jours, Claudette said: “She’s working hard, but she doesn’t have control over her muscles. What breaks my heart is that she’s always been disciplined. She’s always worked hard. Our mother always told her, ‘You’re going to do it well, you’re going to do it properly.’ It’s true that in both our dreams and hers, the goal is to return to the stage. In what capacity? I don’t know.”

While research is ongoing into the condition, the rarity of it means progress has been slow.

Celine announced last December that she had postponed her 2023 European tour as a result of the condition.

“While we’re still learning about this rare condition, we now know this is what’s been causing all of the spasms that I’ve been having. Unfortunately, these spasms affect every aspect of my daily life, sometimes causing difficulties when I walk and not allowing me to use my vocal cords to sing the way I’m used to,” Celine said in a video posted to social media.

Stiff person syndrome is characterised by severe muscle spasms and rigidity in the torso and limbs. The muscle spasms can occur at random or be triggered by certain stimuli, including loud noises, touch and emotional distress.

Claudette added: “The vocal cords are muscles, and the heart is also a muscle. This is what comes to get me. Because it’s one out of a million case, the scientists haven’t done that much research because it didn’t affect that many people.”

Celine’s family charity, Fondation Maman Dion, has been inundated with messages of support for the star.

Claudette said: “Some people have lost hope because it’s an illness that isn’t well known. If only you knew the number of phone calls the foundation gets about Celine! People tell us they love her and they’re praying for her. She gets so many messages, presents and blessed crucifixes.”

Claudette has previously revealed that despite working with “the top researchers in the field”, her 55-year-old sister has seen little improvement in her health.

She told Le Journal de Montreal: “We can’t find any medicine that works, but having hope is important.”