A year after Celine Dion revealed her stiff-person syndrome diagnosis , her sister is sharing an update on the five-time Grammy winners health.

In an interview with 7 Jours , a French-Canadian outlet, Claudette Dion said her famous sibling doesnt have control over her muscles.

There are some who have lost hope because it is a disease that is not [very well] known ... What pains me is that she has always been disciplined. Shes always worked hard. Our mother always told her, Youre going to do it well, youre going to do it properly, she said.

Although Celine Dions family is hopeful shell be able to resume performing one day, its uncertain if that will happen.

Its true that, in both our dreams and hers, the goal is to return to the stage. In what capacity? I dont know, Claudette Dion said. The vocal cords are muscles, and the heart is also a muscle.

A representative for Celine Dion did not immediately respond to HuffPosts request for comment.

The National Institute of Neurological Disorders and Stroke defines stiff-person syndrome as a rare, progressive neurological disorder that can cause muscle spasms. The condition can be so debilitating that some develop a hunched posture that prevents them from walking or moving independently at all.

It affects approximately one in 1 million people and is twice as common in women than men. There is no cure.

Celine Dion first confirmed her diagnosis in a short video shared on her social media accounts in December last year. At the time, she said her condition required her to postpone and cancel some concerts that had already been rescheduled due to health issues .

In May, all of her remaining concerts were officially canceled .

Though Celine Dion has maintained a low profile since sharing her diagnosis, she appeared to be in good spirits last month when she attended an NHL hockey game with her and late husband Ren Anglils sons Ren-Charles, 22, and Nelson and Eddy, both 13, in Las Vegas. The game marked her first public appearance in more than three years.

My boys and I had such a fun time visiting with the Montreal Canadiens after their hockey game with Vegas Golden Knights in Las Vegas Monday night, she later wrote on Instagram . They played so well, what a game!! Thank you for meeting us after the game, guys! That was memorable for all of us. Have a great season!