A 13-year-old Toronto girl with Down syndrome is making waves in the entertainment industry after her cover of John Legend's hit "All of Me" went viral.

Madison Tevlin recently covered the chart-topping song with the help of her vocal coach. The video was uploaded to YouTube last month and has since had more than 4.5 million views.

Earlier this week, John Legend himself retweeted a link to a story about Tevlin's video. The rising YouTube star ecstatically responded to that tweet on Wednesday, messaging him directly: "Oh my god! @johnlegend I cannot believe that you saw my video! This is so cool, thank you so much! I just love you!!"

The YouTube video also got the attention of Hollywood actor Ashton Kutcher, who shared it on Twitter.

Tevlin's passion for singing may also land her a role in a Hollywood film. A casting director recently expressed an interest in having the Toronto teen audition for a movie.

"I was not expecting this. It was so crazy," Tevlin told CTV News Channel Tuesday, referencing the positive feedback she’s received about her performance.

And it's not just Tevlin who has been kept busy over the past few days. Tevlin's mother, Grace, has been fielding media calls from people who are interested in interviewing her daughter.

"Everyone has been calling my mom," Tevlin told CTV Toronto on Wednesday. "They want to interview me."

Prior to filming the video, Tevlin said she practiced "a lot" to perfect her performance. She says she hopes the video will reach 21 million views by March 21 in honour of World Down Syndrome Day.

Unlike most teenagers, however, singing is more than about hitting the right key for Tevlin. According to the National Down Syndrome Society, children and adults with the condition generally face communication challenges, such as composing sentences.

Tevlin's vocal coach Marla Joy adds that people with Down syndrome usually also have tonal issues.

"Down Syndrome children should have low, monotone, gruffy voices. They have problems with hearing and shouldn’t be able to memorize as easily," she told CTV Toronto on Monday.

But those challenges have not stopped Tevlin from breaking out into song whenever she can.

The Toronto teen says her parents signed her up for classes because she would often sing while riding in the back of their car.

"My mom and dad, both of them, said to me that I was too loud for them at the back of the car … so they put me in singing lessons," she said on Tuesday.

Tevlin also owes some of her online success to her sister Zoie Tevlin, who manages her Instagram, Twitter, Facebook and YouTube pages.

Zoie says working with her sister is "really inspiring" because "it makes you want to do even more."

The pair posted a new video on YouTube Monday, thanking Tevlin's supporters for their “wonderful comments and messages.”

Tevlin's mother, Grace, says she is "extremely proud" of both her girls.

"They are inspiring so many others to achieve if you really work hard at something," she said.

She adds that her daughter's YouTube video is also helping to raise awareness about Down syndrome.

"People are looking at children or adults with special needs and they're seeing them for their abilities and their strengths."

With a report from CTV Toronto's Dana Levenson