Transcript for 4-year-old with rare blood disease meets her favorite singer
Finally tonight here, our person of the week. The little fighter and her giant voice. It began with a song you saw right here. And it turned out, many were listening, and they're now answering the call to be the match. Tonight, right here, meet our person of the week. This is how the video starts. Her shoulders moving, little Leah Carroll. Lip syncing to start, she's just 4 years old, born with a rare blood disease. A thumbs-up after overcoming two bone marrow transplants. Her mother by her side there. And on the video, mom encouraging her little girl. Let me hear it. Really awesome. ??? You might be down for a moment feeling like it's hopeless ??? ??? that's when he reminds you that you're an overcomer ??? "You're an overcomer," the song goes, and Leah singing nearly every word. After spending over 400 days away from her family, music has helped Leah get through it. With over 8 million views, the video caught the attention of the artist who sings that song, mandisa. And this week mandisa paying Leah a visit. I'm with somebody very special right now. Mandisa's new friend couldn't wait. And she is jamming. It turns out, Leah had a special gift for her favorite singer. The two of them singing together. ??? Wish I could be part of that world ??? Mandisa giving a concert at Leah's church, raising thousands to support the bone marrow registry called be the match. Leah's singing already generating hundreds of new donors. And tonight, the people at be the match, grateful to that little fighter using her voice. ??? You're an overcomer ??? So we choose Leah.
This transcript has been automatically generated and may not be 100% accurate.