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Scott G Winterton, Deseret News
Trey and Heidi Wallis, with their son, Louie, talk about why they are fighting to have GAMT screening placed on the national newborn screening list during an interview in their Bluffdale home on Wednesday, Nov. 2, 2016. Two of their children — Louie and Sam — have the rare disease guanidinoacetate methyltransferase (GAMT) deficiency.

BLUFFDALE — Louis and his sister Sam share a lot of things: The same pale skin. The same chestnut hair. The same curious eyes.

They also share the same rare inherited disorder, one with a name so long that scientists simply refer to it as GAMT. It stands for guanidinoacetate methyltransferase deficiency.

Thirteen-year-old Sam, who loves dancing and biking, has serious developmental delays that have impeded her speech and learning.

Four-year-old Louis, who loves Five Guys and is excited about kindergarten, talks quickly and breathlessly, and loves to make up games and stories — things that Sam still doesn’t do, mother Heidi Wallis notes.

The difference is that Sam wasn’t diagnosed until she was 5 ½ years old. Louis was diagnosed and started on treatment as a newborn.

Diagnosing and treating kids with GAMT deficiency is both cheap and easy to do, as scientists at the University of Utah and ARUP Laboratories have discovered. Yet Utah is the only state in the U.S. that screens for the genetic disorder.

Wallis and her husband struggled with grief and guilt for years, wondering if there was more they should have done for Sam.

Now, they have a mission: Ensure that all children in the U.S. are screened for GAMT at birth.

Wallis — along with ARUP Laboratories biochemical genetics director Marzia Pasquali and University of Utah Health Care medical genetics chief Nicola Longo — will make their case Thursday to a national committee that advises the U.S. Department of Health and Human Services on which disorders to include in newborn screening panels.

“You feel desperate not to let it happen any more,” Wallis said. “I want every child born with GAMT, for their parents to know right away that it’s treatable.”

Utah added GAMT to its newborn screening panel in June 2015 at the request of Longo and Pasquali, who have 10 years of experience treating patients with GAMT deficiency.

“The committee felt in a way that this was an easy one to vote on,” said Utah Department of Health newborn screening program manager Kim Hart.

Pasquale developed the screening test years ago. The test measures the amount of a compound called creatine in the blood. Kids with GAMT cannot create this compound, which is necessary for healthy brain and muscle development.

The test is cheap — less than 25 cents per sample, according to Hart. And it required just 3 micrograms of blood, collected through a heel stick.

“Someone has to start,” Hart said. “And why not Utah be on the forefront of it?”

Left untreated, GAMT deficiency has devastating consequences, including intellectual disability, recurrent seizures and delayed motor skills. For children who are not diagnosed until they are toddlers, the difference “is basically day and night,” Longo said.

“They continue to learn, but they never reach normal potential,” he said. “With treatment at birth, there is no difference from healthy.”

GAMT deficiency is so rare and its symptoms so varied that many pediatricians do not diagnose it until the damage is done. It is often misdiagnosed as autism or cerebral palsy.

Wallis began worrying about Sam when she was about 18 months old because she wasn't talking. At 3 years old, Sam was diagnosed with autism. By age 5, Wallis noticed Sam would frequently stop talking in the middle of a sentence and look upward.

Eventually, a neurologist confirmed Sam was silently seizing up to 100 times a day and that she had a GAMT disorder.

With treatment, Sam has made strides, but she continues to have convulsive seizures every one to three weeks and is still at a first- or second-grade level when it comes to schoolwork, according to Wallis.

“Cognitively, she hasn’t made up for those five years,” Wallis said.

Longo perfected a simple treatment. Because the disease prevents kids from synthesizing creatine, Longo has Sam and Louis take supplemental creatine either in pill or powder form. And because the disorder also causes toxic buildup in the brain, the kids take another amino acid supplement called ornithine to get rid of it.

The supplements, taken with lunch or dinner, cost about 50 cents a day for Louis and $1.29 a day for Sam, according to Wallis.

And they have entirely prevented any developmental or cognitive delays in Louis, who looks forward to going to kindergarten.

It takes "such minimal effort, and it makes such a big difference. I think it's kind of a no-brainer," Pasquali said. But intervention needs to take place early, before the first year of life, and preferably at birth.

There are downsides to consider with any request to add a disorder to a newborn screening panel, Hart said.

For one, every additional test will increase the cost of the screening kit. For some disorders, there are no reliable screening methods or effective treatments.

And then there are the ethical gray areas that medical providers are increasingly bumping up against. Sometimes screening can detect when a baby does not have a disorder but is a carrier of the gene. Should they inform the family that the child has a possibility of passing it on?

Luckily, GAMT deficiency raises none of those concerns, Hart said. “This was actually refreshing,” she said, because the diagnostic test is cheap and the treatment is effective.

In May, the national committee voted against adding GAMT deficiency to its recommendation list, 7-6, after heated debate. Members wanted to see at least one case of GAMT be identified by a newborn screening program, Pasquali said.

But the disease is rare — with a prevalence of about 1 in 120,000 children, by Pasquali and Longo's estimation — and Utah is a small state. The state screening program has not identified any babies with the deficiency.

To their surprise, however, the national committee invited Longo, Pasquali and Wallis back to discuss the case.

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If approved, the case will move to an evidence review board before landing on the desk of Secretary of Health and Human Services Sylvia Burwell for her final stamp of approval.

For Pasquali and Longo, it's a one-of-a-kind opportunity to change the course of the lives of dozens of children a year.

"It is an honor to work with them," Pasquali said, of the Wallises and other families who have struggled with GAMT deficiency. "We have an obligation to give these children the best chance they can get."

Email: dchen@deseretnews.com

Twitter: DaphneChen_