Girl Turns Ailing Brother Into 'Superhero'

Makenzie Lawrey wrote "The Mighty Mito Superhero" after her brother was diagnosed with a mitochondrial disease.
3:00 | 02/07/14

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Transcript for Girl Turns Ailing Brother Into 'Superhero'
A real sister act here one little boy in Florida is fighting an incurable disease by his big sister. Aside and determined. To help the -- Gavin is only six and dealing with something so much larger that he can comprehend. Mitochondria. It attacks the cells and for the most part. Zaps his youthful energy and causes seizures and that. Is where his big sister comes at MacKenzie she wrote a book about -- struggles. Does not selling it hoping to make money to race for research on the disease. Hopefully I can raise a million dollars in less than a million dollars -- -- -- Matt -- has now. Not there yet but. McKenzie is doing pretty good. She's raised 20000 dollars in just a week the book is called the mighty -- go super hero and you can follow -- always progress. -- was FaceBook page.

This transcript has been automatically generated and may not be 100% accurate.

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