When Santa arrives at 4-year-old Michael Gonzalez's house in Florida, he won't find milk and cookies under the tree.

That's because Michael is allergic to every food he's ever tried except for raw hemp seeds, pure cane sugar and a formula for highly allergic children called Neocate. Food is kept locked away in the kitchen as if it were poison.

As a result, the Gonzalez family is skipping Christmas dinner altogether.

"He's sad to see other people eat, and doesn't understand why it doesn't hurt our tummies when it hurts his tummy," his mother, Jennifer Gonzalez, told ABCNews.com. "It's not fair that we can and he can't."

Read about Michael's reaction to Neocate, which no longer works for him.

Michael was born weighing only 4 pounds and 4 ounces, though he wasn't premature, Gonzalez said. She soon noticed Michael couldn't consume breast milk without vomiting or having diarrhea.

Doctors eventually diagnosed Michael with food protein-induced enterocolitis syndrome, or FPIES, which renders people unable to eat certain proteins without getting sick. Doctors told Gonzalez her baby would grow out of it.

He never did.

Despite undergoing food trials to train Michael's immune system to recognize food as fuel, he was still getting sick. Eventually, food started to give him seizures.

Last month, after years of questions, Michael was diagnosed with mitochondrial neurogastrointestinal encephalopathy disease, or MNGIES, a genetic condition that affects the digestive and nervous systems, Gonzalez said. Only about 70 people have ever been reported to have had it, according to the National Institutes of Health.

"We're glad they found it in his DNA," his mother said, explaining that it's a relief to finally have an answer even if the outlook is scary. People with MNGIES, she was told, only live till about 30 years old.

Her hope, she said, is that Michael can undergo a bone marrow transplant that will give him a chance at a more normal life.

Even though Michael had to give his candy cane back to the mall Santa, and even though Gonzalez left the Christmas ornaments in their boxes this year because they gave Michael a reaction, Gonzalez said she'll still try to give Michael the best Christmas she can.

"He knows he's sick. He knows something's wrong. But we don't let him know everything," Gonzalez said. "He needs to look at the world like it's huge and ready to explore, not like the world is out to get him."