The season five alum tells THR the story behind her Christian hit; Also: Jordin Sparks and boyfriend Jason DeRulo will release a duet, but they’re already (almost) together on the Billboard Hot 100.

(OAKLAND, Calif.) -- 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 ...