Girl with rare disease singing "Overcomer" in viral video meets Grammy winner behind song

— -- Earlier this year, 4-year-old Leah Carroll, a California child who has a rare blood disease, lifted spirits worldwide when her rendition of the song "Overcomer" by Grammy winner Mandisa went viral.

But this week, it was Leah's turn for a bit of uplifting when Mandisa came to UCSF Benioff Children's Hospital Oakland to meet the petite songstress for the first time, sing and play.

"Y'all, I'm with somebody very special right now," Mandisa said during a Facebook Live video she shared with fans Wednesday. "This is amazing. It's bringing me so much joy."

Leah was born with severe congenital neutropenia. In February 2014, she had her first bone marrow transplant, and in March 2016, she underwent her second transplant. Since then, she has been recovering in the hospital in Oakland, California because of complications.

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On Wednesday, Mandisa also held a private concert at Leah's church, participated in a discussion about Be the Match Registry and later joined her. The event helped raise $3,600 for Be the Match.

Click here for more information on Be the Match Registry.

During the discussion, Lindsey Chapman-Carroll, Leah’s mother, shared that Tuesday would be the girl's 430th day spent in the hospital and away from her home and family.

Chapman-Carroll said that she and Leah had a goal of signing up 430 new marrow donors by Tuesday. So far, about 400 people have signed up in Leah's honor.

"It's just so cool. God is in every detail. ... People have really stepped up their registering game," Chapman-Carroll said.