Big brother, 4, is superhero donor to younger siblings

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Four-year-old Michael looks like your average little boy. He loves to play with his toys and his older brother Dominick. But, he's an extraordinary kid who at such a young age has made the decision to do something most of us haven't and may not ever do.

"He's just like, 'I'm a real-life superhero.' He says I'm going to save my baby brothers,” Michael's mother Robin explained.

GOFUNDME: Hope for the Pownall/Demasi Family

In two weeks, Michael will undergo a bone marrow transplant to save the lives of his 4-month old twin brothers Santino and Giovanni. His incredible strength makes his mom emotional.

"He goes to the doctor when he gets the labs for the pre-testing and he says look how strong I am and he gives them willingly his arm to get blood work. The nurses are amazed. They're like 'I cannot believe how brave he is,' and he really is. It gives me chills,” said his mother Robin Pownall.

Santino and Giovanni are at CHOP in need of the transplant because they were diagnosed with Chronic Granulomatous Disease. It’s a rare immune disorder. Only one in 500,000 people are diagnosed a year. It affects mostly boys and it can be deadly. The oldest son Dominick was born with CGD too, but received a stem cell donation from an outside donor. Michael doesn’t have it.

"We knew it was a chance but for it to happen again to both babies we were in shock at first," said Pownall. Doctors determined Michael was a match for both of his twin brothers. A few hours after the transplant he will get to watch his baby brothers infused with his bone marrow.

"He could have said no mommy I'm too scared and I don't want to but he's ready to go and he's our real life superhero," said Pownall. She and her fiancee have both quit their jobs. She's at the hospital with the twins and he's home with the other two boys. They have a Pownall/Demasi Family GoFundMe page for anyone who wants to donate to help them with medical expenses and bills. The surgery is March 8.

Michael, Dominick, and their mother Robin appeared on Good Day Philadelphia Friday morning to talk more about their story. You can watch more in the videos above.