Reports began to surface that McGarrigle, 63, was ill last weekend, after her son Rufus canceled a string of dates in Australia and New Zealand because of “an illness in the family,” according to the CBC.

The singer’s brother-in-law, journalist Dane Lanken, confirmed to CBC that her death was caused by a rare form of cancer.

McGarrigle’s musical career began in the ’60s while she was still an engineering student at McGill University in Montreal.

The singer told The Canadian Press in 2005 that despite the objections of their father, she and her older sister Anna began performing on the local folk scene, where they soon became fixtures.

“He would have hated the idea of us becoming professional musicians because he thought professional musicians were bums, people that wandered from town to town,” McGarrigle explained.

Over the next three decades the McGarrigle Sisters recorded 10 albums (in both English and French); performed with acts like The Chieftains, Leonard Cohen, Joan Baez, Bryan Ferry, Nick Cave, Jarvis Cocker, Lou Reed and Van Dyke Parks; made numerous television appearances including 1998’s “The McGarrigle Hour” and had their songs covered by artists from Billy Bragg to Linda Ronstadt, whose cover of the sisters’ “Heart Like a Wheel” was the title track of her 1974 commercial breakthrough album.

Although Kate and Anna released their final album, The McGarrigle Christmas Hour, in 2005, the singer continued to perform occasionally on her own and with her children.

Rufus Wainwright has often credited his mother and his father, Loudon Wainwright III, with providing the foundation of his career.

“The truth is, I’ve drawn a lot of my creative inspiration from Mum and her background,” the singer told London’s Telegraph. “She’s a very earthy, very instinctual woman, and that comes out in her music. I knew very early on that, like her and Dad, I wanted to be a singer-songwriter.”