Bo Jungmayer / Fred Hutch News Service
Ezra Dixon was born April 7, four months after the state of Washington first started screening newborns for the disorder commonly known as “bubble boy disease,” which leaves its victims at the mercy of common germs.
Some 22,610 babies were tested before him and more than 28,000 have been tested since, all negative, health records show. But Ezra is different.
The bald, blue-eyed boy is the only child in the state so far diagnosed with severe combined immunodeficiency, or SCID, detected through the program.
When lab staff analyzed the drop of blood pricked from his heel shortly after birth, they found none of the T-cells that protect the body from infection, a certain sign of the rare disorder.
The news that their 3-day old baby had a rare and potentially fatal disease was a shock to Ezra’s young parents, Rachel Dixon, 24, a former apartment manager, and Zach Dixon, 25, a construction worker, both from Spokane, Washington.
They recognized SCID only from popular TV shows and the old John Travolta movie, “The Boy in the Plastic Bubble,” inspired by David Vetter, a Texas boy who had the disease.
“The most I’d ever known about immune deficiency was what I’d seen on ‘House’,” recalls Rachel Dixon. “We spent a couple of days thinking we’d have a ‘bubble boy’ for the rest of our lives.”
The couple, who are ministry students temporarily living in Arlington, Washington, turned to family and faith for support. They pointedly avoided the Internet. “I did not want to open the door to fear,” she said.
But their worry quickly turned to relief when the Dixons learned that, unlike David Vetter, who died at age 12, their baby could be treated and even cured. Ezra’s condition was detected early, before he developed a life-threatening infection tied to his impaired immune system, and he was able to receive a bone-marrow transplant when he was eight weeks old.
The catch? The best stem cells would come from his brother Judah, 20 months, who turned out to be a perfect match.
“It was tough,” said Rachel Dixon, of the decision to put both boys through difficult medical procedures. “But it was either this or he doesn’t live.”
Within two weeks, healthy cells from Judah had already engrafted, or taken hold, offering Ezra a promising future – and underscoring the results of a new study involving Fred Hutchinson Cancer Research Center and Seattle Children’s Hospital researchers.
Published last week in the New England Journal of Medicine, the study led by Boston Children’s Hospital researchers confirmed what specialists have long believed: that children with SCID can be cured with stem cell transplants from siblings and others, but that early treatment is the key.
“Regardless of what source you use for the bone marrow graft, if you are transplanted at less than three months of age, you have a 94 percent chance of survival,” said Dr. Suzanne Skoda-Smith, clinical director for the Division of Immunology at Seattle Children’s.
Skoda-Smith and her colleague, Dr. Lauri Burroughs, an assistant member in the Clinical Research Division and Pediatric Stem Cell Transplantation Center at Fred Hutch, were among researchers who provided data from 240 babies with SCID who received transplants at 25 centers from 2000 to 2009.
Burroughs developed the chemotherapy protocol used to treat Ezra Dixon and she has monitored his care.
The new study was the first large-scale review of bone marrow transplants for SCID, which affects about 1 in every 50,000 babies in the U.S. Many children with SCID who are undiagnosed and untreated die from infections in the first year or two of life.
The new study showed that survival rate was best among infants who received sibling donations, but that regardless of the donor type, survival at age 5 was indeed 94 percent among babies who received transplants at or before 3 ½ months. That’s a critical time marker because antibodies transferred from the mother during pregnancy typically wear off starting around 4 months. It was 90 percent among older babies who hadn’t had infections and 82 percent among those who had infections that resolved.
Survival was lowest, only 50 percent, among babies who were older than 3 ½ months and had active infections at the time of transplant.
“Here’s the recurring theme: We’ve got to prevent those infections,” Skoda-Smith said.
For transplant scientists, the study re-emphasizes the need for newborn screening for SCID, which in 2010 became the 31st condition added to the recommended uniform screening panel compiled by the U.S. Health and Human Services Department.
“We always teach that SCID is a pediatric emergency,” said Dr. Donald Kohn, director of the Human Gene Medicine Program at the University of California, Los Angeles. “And if someone is diagnosed with SCID, they need to get transplanted immediately. But they have to be diagnosed.”
Today, 21 states and the District of Columbia already screen for SCID, another 10 states and Puerto Rico plan to start this year and three more states have agreed to screen, but don’t have a timetable for implementation, according to the Immune Deficiency Foundation.
That leaves at least 16 states where there are no plans to screen babies like Ezra, who appeared completely healthy at birth. Without screening, SCID is typically detected only when a child develops an infection, usually at about age four to six months, Skoda-Smith said.
Still, implementing the screening has been controversial – in Washington state, it took three years to get it approved by the state legislature, she said.
Courtesy of the Dixon family
Critics of newborn screening often argue that the benefit of detecting the one child in 50,000 with the rare disorder doesn’t justify the public health cost of screening. That’s despite the huge costs of transplanting just one baby with SCID and an active infection, Skoda-Smith noted.
That line of thinking appalls Rachel Dixon.
“They had to put a dollar amount on the life of a baby,” she said. “This is something that you can’t know about until something goes wrong.”
Today, more than 50 days after transplant, Ezra is doing well, his mother said, cradling the baby who gurgles and smiles at her touch.
There’s no sign so far of graft-versus-host disease, a potentially deadly complication in which the donor cells attack the host's healthy organs. About 20 percent of transplanted babies develop acute GVHD in the first 100 days after transplant and about 15 percent have a chronic form of the condition at age 2 years, the study showed.
Side effects from Ezra’s chemotherapy treatment have subsided, as has an infection that left blisters on the lining of his throat and digestive tract, preventing him from eating normally. He’s still using a yellow feeding tube held in place with a bright duck sticker, but the cheerful baby who lights up at his mother’s smile doesn’t seem to mind.
After months of staying with grandparents, with only brief visits with mom and dad, Judah has joined Rachel and Zach Dixon at Seattle’s Ronald McDonald House, where they’ll spend the rest of the summer. It’s still not quite clear when Ezra will be able to go home, his mother said.
“It’s been 16 weeks since we’ve been together as a family,” Rachel Dixon said.
The ordeal has opened her eyes to what she believes is the need for universal newborn screening for SCID – and for more people to donate bone marrow. When people ask the young mother what they can do to help, she urges them to sign up with Be The Match, the bone marrow registry operated by the National Marrow Donor Program.
“Even if you can’t help Ezra, if you can help some other kid in the future, it means as much to me as helping my kid,” she said.
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JoNel Aleccia is a staff writer at Fred Hutchinson Cancer Research Center. From 2008 to 2014, she was a national health reporter for NBC News and msnbc.com. Prior to that she was a reporter, editor and columnist for more than two decades at newspapers in the Northwest. Reach her at firstname.lastname@example.org.
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