He's Trying to Save His Sister From a Disease He Doesn't Know is Terminal - You Can Help! (VIDEO)

(Screenshot: The VonWong/YouTube)

Beckham O'Neill, 7, knows his 4-year-old sister Eliza has "a very bad disease." He knows it's called Sanfilippo Syndrome and it "clogs up her brain and makes her not learn very well." He's right. The genetic disorder prevents the breakdown of a toxic material called heparan sulfate in the brain and body, leading to severe disability and death.

There is no cure for Sanfilippo Syndrome. Yet.

In this video, Beckham asks viewers to help Eliza pay for the "medicine" she needs, which is actually a pioneering gene therapy trail specifically for children with Sanfilippo Syndrome. He doesn't know the tragic consequences if she doesn't get it – and he doesn't have to.

To help Eliza receive her therapy, visit SavingEliza.com.