An 8-year-old California boy has raised nearly $1 million dollars in sales of a self-published book for his friend with a rare disease.

Dylan Siegel wrote the book “Chocolate Bar” about a boy who dreams that his words and pictures will help find a cure for his best friend’s illness— and change the world. The book was published in 2012, and it has since raised over $900,000.

According to the book’s website, “chocolate bar” means “awesome” to Siegel.

Siegel’s friend, Jonah Pournazarian, has a rare liver condition called Glycogen Storage Disease 1B. Pournazarian was diagnosed at 6 months and his body is unable to digest sugars, Rabin Pournazarian, his dad, told KTLA in 2013. The Pournazarians monitor everything he eats to keep his blood sugars from spiking and he is fed special formula thorugh a tube in his stomach.

“I am so so, so excited to be able to help my friend,” Siegel told CBS LA. “I am thankful to people everywhere for letting me share my story and inspire kids to change the world.”

Siegel, Pournazarian and students at Wise Elementary School in Los Angeles celebrated the two-year anniversary of the book on Sunday. The boys read the book to their audience, and took photos and signed autographs. Students also received chocolate bars, bracelets, tattoos and T-shirts.

Donations are going toward the University of Florida, where research is underway to help find a cure. Those who are interested in making a contribution can purchase the picture book online.

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