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OTRC: Justin Bieber mourns 6-year-old fan Avalanna Routh

Justin Bieber appears in a photo from teh Billbaord Music Awards on May 20, 2012. / Bieber appears in a photo with Avalanna Routh, posted on his Instagram.

Justin Bieber mourned the death of one of his biggest fans on Wednesday, September 26, a 6-year-old girl named Avalanna Routh.

Routh was a Massachusetts native who loved Bieber so much she called herself Mrs. Bieber. She battled a rare brain cancer and last year, doctors and nurses organized a pretend wedding to the pop star, according to the Associated Press.

"Our darling Avalanna went to Heaven this morning," a Tweet from her Twitter account, which her family shared, said. "Oh Avalanna, the brightest star - you took our hearts with you, our greatest Love;(."

The pretend wedding, where Routh wore a T-shirt that said "Future Mrs. Bieber," sparked a Facebook campaign to help her meet the singer.

Bieber met Routh in New York earlier this year and the two spent a couple of hours together. They met several times after that initial meeting.

Routh suffered from a fast-growing tumor called an atypical teratoid rhabdoid tumor, according to the wire service. The tumor affects the brain and spinal cord and usually occurs in young children. Only 30 new cases are diagnosed in the U.S. each year.

The 18-year-old singer wrote about the news to fans on his Twitter page, writing, "Just got the worst news ever. one of the greatest spirits I have ever known is gone. please pray for her family and for her."

"RIP Avalanna. i love you," he said in another Tweet.

"Please show respect to her and her family. say a prayer for her and for them. i miss her," he later wrote.

Bieber later posted a picture of himself with Routh on his Instagram account with a caption that said, "My angel."

"She was a very courageous young person who lived her life with grace and determination," the Dana-Farber Cancer Institute, where Routh received treatment, said in a statement. "By generously sharing her story, she raised awareness worldwide about atypical teratoid rhabdoid tumors and articulated the need for greater research of this rare cancer."

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