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 / Updated  / Source: TODAY contributor
By Michael Inbar

Amylynne Santiago Volker calls her 6-year-old son Nicholas “the comeback kid,” and rarely has that title been more fitting: Nic has survived a mystery illness that baffled doctors and threatened his life many times.

Doctors call Nic a medical marvel, a trailblazer who escaped near-certain death through a groundbreaking DNA sequencing and a rare cord blood transplant.

Speaking live via satellite from Madison, Wis., Santiago Volker told Matt Lauer on TODAY Monday that she remains in awe of the strength her little boy showed in enduring countless surgeries and 700 days of hospital care — 526 days in the last two years alone.

“Nic is so resilient and he always faced every day with a smile on his face,” Santiago Volker said.

While Nic hugged a teddy bear and traded high-fives with his dad, Sean Volker, on TODAY, his mother told Lauer of their family’s medical ordeal.

He was just 17 months old when his parents noticed Nic had a wound that wouldn’t heal. When the wound became an abscess, he was taken to a local hospital, where he was given antibiotics. That marked the beginning of an excruciating, four-year medical journey.

A deadly disease, but no diagnosis
While Nic was shuffled in and out of hospitals, doctors learned the boy suffered from a disease that caused pencil-prick-size holes to form on his skin. The holes traveled through to his intestines, causing his stool to leech into his system. He developed sepsis, ran a temperature of 105 degrees and also contracted E. coli from his breathing tube.

They knew he was very sick, but they didn’t know why. Doctors couldn’t figure out what was causing Nic’s problems or put a name on his illness, and thus couldn’t help him get well.

When Nic was 4, doctors removed his colon, which Santiago Volker told Lauer seemed to help initially. “He was able to walk and run around and climb for the very first time,” she said.

But Nic’s health started to fail again just weeks later, and he began another round of hospital stays. At age 4, he weighed only 17 pounds. Doctors at the Children’s Hospital of Wisconsin realized that they had to nail down the cause of the boy’s ailment. They asked the hospital’s researchers to sequence Nic’s 30,000 genes to see if one was mutated.

Hospital immunologist Bill Grossman told NBC News it is extremely unusual to sequence the entire genetic code of one person — his team usually works on abstract DNA research. “I was shocked [by the request],” Grossman said. “It was a big leap for what we were currently doing.”

Meanwhile, the Volkers tried to hold their family together. Santiago Volker worried that the couple’s three teenage daughters were getting short shrift while the family concentrated on Nic’s life-and-death struggle. Sean Volker worked overtime in construction to pay the medical bills insurance didn’t cover; when his work dried up, mom went back to work while dad became the primary caregiver.

DNA sequencing solves a mystery
But the family struggle and exhaustive hospital research paid off. Thanks to the gene sequencing, Nic was diagnosed with the genetic mutation XIAP, and doctors realized a cord blood transplant — which would essentially give Nic a new immune system — could be a possible cure. In July, Nic got the transplant.

“We saw an improvement in the first two weeks,” Santiago Volker told Lauer. “He was extremely active, played like a normal boy would. Lots of sword fights, and lots of floor time with his sisters and his dad and myself.”

Nic has suffered some complications and setbacks since, but he has kept his spirits up. During his long hospital stays, he donned his favorite Batman costume, complete with bat gloves that sound “kapow!” His mother told the Milwaukee Journal Sentinel Nic likes the musical trio the Jonas Brothers, and she had heard him sing a line from their song “A Little Bit Longer,” which goes, “A little bit longer and I’ll be fine.”

Hopefully, that will be the case for Nic. Santiago Volker told Lauer that her son’s prognosis “is extremely good. His [transplant physician] thinks he will be a long-term survivor. And that he’s possibly cured.”

Nic curled up in his dad’s arms for a nap while appearing on TODAY. But his parents clearly never tired of fighting his mystery illness. Nurses at the Children's Hosptial of Wisconsin told the Journal Sentinel they were amazed at how Santiago Volker dressed to the nines during daily hospital visits, never giving in to hopelessness over her son’s condition.

Likewise, Santiago Volker shooed away well-meaning relatives who told her the family needed to plan a funeral or sign a “do not resuscitate” order.

“I relied on my faith, and I had to hold on to hope,” Santiago Volker told Lauer. “[I] always tried to just persevere and get through the next step and just hope there was another miracle.”

Doctors see a bit of a miracle in Nic as well. If he continues to improve, his case may give hope to others with mystery ailments that could be identified through DNA sequencing.

For more about Nicholas Volker’s story, visit the Milwaukee Journal Sentinel online by clicking here.