Celine Dion's sister has shared an update on the singer's health as she continues to seek treatment for stiff-person syndrome.

The "My Heart Will Go On" singer announced in December that she had been diagnosed with the rare neurological disorder, which can cause muscle rigidity and muscular spasms.

Sharing an update on her condition, Dion's sister, Claudette Dion, said in an interview with the Canadian publication Le Journal de Montréal published in July that another sister, Linda, had moved into the singer's home to aid in her care.

"When I call her and she's busy, I speak to my sister Linda who lives with her and tells me that she's working hard," she said.

"I honestly think that she mostly needs to rest. She always goes above and beyond, she always tries to be the best and top of her game," she continued. 

Speaking about Dion's decision to step away from performing, Claudette said: "At one point, your heart and your body are trying to tell you something. It's important to listen to it."

"It's innate to her, she's disciplined in every area of her life. We can't find any medicine that works, but having hope is important," said the singer's sister.

Claudette Dion added that the "Love Again" star is "listening to the top researchers in the field of this rare disease as much as possible."

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

As Insider's Marianne Guenot previously reported, there is no cure for stiff-person syndrome, but it can be managed using specific antibody injections, anti-anxiety drugs, and muscle relaxants. 

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It is a disease that progresses over time, and if left unmanaged, can become debilitating. 

The 55-year-old Grammy-winning artist shared her diagnosis in December 2022. In an emotional video posted to Instagram, she said: "I've always been an open book. I wasn't ready to say anything before, but I'm ready now."

"I've been dealing with problems with my health for a long time. It's been really difficult for me to face these challenges and to talk about everything I've been going through," Dion said. 

"Recently, I've been diagnosed with a very rare neurological disorder called stiff-person syndrome, which affects something one in a million people."

In light of the diagnosis, the singer rescheduled several of her upcoming tour dates in 2023 and 2024. In May, she called off the tour for good.