SAN DIEGO – An 8-year-old boy with a rare, genetic disease has died a day after being made an honorary Marine, his father said.

Wyatt Gillette died Sunday with a developmental disorder that causes seizures and kidney failure, his father, Jeremiah Gillette, told the Marine Corps Times.

Wyatt was honored in a formal ceremony Saturday at Camp Pendleton near San Diego, where his father serves as a drill sergeant.

Video and photos of the ceremony show Wyatt dressed in fatigues and seated in his wheelchair while being presented with a framed certificate and an official Marine Corps pin.

Marine Corps Commandant General Robert Neller agreed to make Wyatt an honorary Marine in response to a petition.

The honor is bestowed on just a few people every year and recognizes civilians who have made extraordinary contributions to the Marine Corps.

Neller wrote on his Twitter page that granting the petition was one of the easiest decisions he had to make as commandant.

“Keep fighting, Wyatt! You are a Marine!” he posted Saturday.

As a 4-year-old, Wyatt was diagnosed with Aicardi-Goutieres syndrome that affects the brain, immune system and skin, as well as causing other complications, according to a press release from the Marine Corps Recruit Depot in San Diego.

When the boy was undergoing dialysis last month, his father reached out to fellow Marines on social media for prayers. An online petition was started that quickly gained supporters.

His father’s command staff began the formal petition process for Wyatt, said Capt. Matthew Finnerty, a spokesman at the Marine Corps Recruit Depot in San Diego.

“His fighting spirit has shown all Marines that although times are tough, we must continue to push on in the face of adversity,” Lt. Col. Jesse Sjoberg, Sgt. Gillette’s commanding officer, said in a statement.

Gillette said he believes his son could have joined the Marines someday if he had been healthy. “He’s the toughest kid I’ve ever met,” he told KABC-TV.