ELIZABETHTOWN, Pa. (AP) — Kennedy Stevenson is a sprite of a child, who gazes at the world around her with serious blue eyes.
Three years old, she has an extremely rare metabolic disorder called S-adenosylhomocysteine hydrolase deficiency, or AdoHcy.
Many parents see their child as one in a million.
"Kennedy," says her mother, Donya McCoy, "is literally one in a billion."
The Elizabethtown girl is one of just eight people in the world who have the same enzyme deficiency.
And because her disorder is so rare, her mother has had to be tenacious and enterprising in her unending quest to get Kennedy medical care.
"Every little step is a battle in this huge war of saving her life," McCoy says.
Kennedy has a petite frame and spindly legs; her diet is severely limited, so she is significantly underweight.
Her feet turn inward, so she wears orthotics, even, sometimes, with her pink Minnie Mouse flip-flops.
Her second toe on each foot is raised ("They have no idea why," her mother says).
Her brain development, her muscles, her nervous system, her liver — all have been impacted by her metabolic disorder.
But Kennedy has learned to say a few words: Mommy, Dada, Wawa (her stepfather), Sissy (her adored and adoring stepsister), "Love you."
She dances when her mother calls for a dance break, and she recently learned to walk, albeit with a stiff, wide-legged gait.
When her mother insists on holding her hand when walking on a gravel driveway, she throws herself on the grass, looking for all the world like an ordinary toddler, having an ordinary toddler's temper tantrum.
"She is awesome," McCoy says. "She is just such a strong, amazing, little person.
"She is so used to being put through pain that when she falls, she just rubs whatever she hit, and moves on. She just battles through everything."
Says McCoy: "We often joke that God was so busy making her so cute that he screwed up a couple of things."
Kennedy was born prematurely on July 23, 2011, at Penn State Hershey Children's Hospital, and spent two months in the neonatal intensive care unit.
At about 8 months, "she had a random seizure," her mother says.
An MRI revealed that the white matter in her brain hadn't developed properly; McCoy remembers the neurologist saying it was "like nothing he'd ever seen before."
And the level of methionine, an amino acid, in her blood was found to be alarmingly high.
Kennedy was sent to The Children's Hospital of Philadelphia and underwent a battery of tests.
McCoy balked, though, when the doctors ordered a spinal tap.
"I said, 'You need a reason before you're going to put a needle in my daughter's spine.' "
McCoy sent her daughter's medical records to Strasburg's Clinic for Special Children, which is known around the world for its research into inherited disease.
Dr. Kevin A. Strauss, the clinic's medical director, told McCoy that there was just one doctor in the United States who could help Kennedy.
And that doctor was S. Harvey Mudd, a researcher at the National Institutes of Health in Bethesda, Maryland.
'AMAZING' DR. MUDD
According to the Washington Post, Mudd's research into metabolic disorders helped to lead "to the routine screening of newborn infants for certain metabolic irregularities."
His research, the Post noted, "led to the practice of putting folic acid into the flour supply to help prevent birth defects. Manufacturers also made changes in baby-food formulas as a result of his work."
Mudd had retired from the NIH in 1987, but continued to work as a scientist emeritus there.
McCoy contacted him in February 2013.
"He diagnosed Kennedy in three weeks," she says.
Mudd and other researchers had identified AdoHcy in 2004. It's a recessive gene disorder; both of Kennedy's parents were the unknowing carriers of a recessive mutation.
Mudd changed Kennedy's diet, monitored her blood tests and consulted "colleagues throughout the world," McCoy says.
Eleven months later, however, Mudd died at age 86.
Marion Mudd, his widow, asked McCoy to speak at the celebration of her husband's life.
"When I met Donya, I just found her to be the most caring of mothers," Marion Mudd says.
And her husband, she recalls, had been "so impressed" by the way McCoy meticulously followed up on his recommendations for Kennedy.
At an idyllic nature sanctuary in Maryland, McCoy told of how she and Mudd had worried that the October 2013 federal government shutdown would close the NIH campus.
One day during the shutdown, her cellphone rang; her caller ID showed it was Mudd calling from his office.
Not even a government closure could keep him from his work.
Mudd was "a Robin Hood for the children he was helping. Authority meant nothing when it came to helping a kiddo," McCoy says.
At the memorial celebration that day, she had two aims: to do justice to the memory of the doctor who had been a savior to her daughter, and to secure the services of the doctor she hoped would take over her daughter's case.
QUEST FOR CARE
Strauss, of the Clinic for Special Children, also had been invited to speak at Mudd's memorial gathering.
En route to Maryland, McCoy told her then-fiance (now husband) Josh McCoy that she needed to convince Strauss to take Kennedy on as a patient.
Mudd had copied her on his emails to Dr. Oliver Vugrek, a molecular geneticist in Croatia, where there were four siblings with AdoHcy.
After Mudd's death, McCoy contacted Vugrek and enlisted his help.
But she needed a doctor here in the United States.
Listening as Strauss paid tribute to Mudd in his "kind and mild-mannered way ... (Josh) leaned over and said, 'Oh that poor guy doesn't stand a chance against you,' " McCoy recalls with a laugh.
After speaking, Strauss had to return to Strasburg, so he handed McCoy his card.
"I pretty much threw Kennedy at Josh and started to walk out with Dr. Strauss," McCoy says. "I was on a mission."
She pleaded her case. "I think he could probably see the desperation on my face and the desperation in my voice."
In the "kindest, calmest voice, he said, 'I'm no Dr. Mudd, but I'll do my best for her.' "
Her voice wavers at the memory.
DR. STRAUSS TAKES OVER
Strauss would be true to his word.
Before she'd even gotten home, Strauss had emailed Vugrek in Croatia, Kennedy's pediatrician and nutritionist, and the Vanderbilt University lab that handles Kennedy's lab work, asking if they could work as a team.
McCoy says she had been "functioning in crisis mode for so long" that the relief of handing off some of the responsibility to a doctor here was overwhelming.
It meant that she could "get back to being the mom. I don't have to be the doctor — because I'm not a doctor."
She says she always felt destined to be a mother.
But "from day one, our journey has been off the beaten path."
She shares custody of Kennedy with her ex-husband, Nicholas Stevenson. "He's a great dad, and very involved, but I've just always handled the medical aspect of things," McCoy says.
Her tenacity on Kennedy's behalf hasn't gone unnoticed.
She was named Pennsylvania's Young Mother of 2014 by American Mothers, an organization co-founded by Sara Delano Roosevelt and Mamie Eisenhower.
She remains a member of Penn State Hershey's NICU advisory board.
Vugrek describes McCoy "as a very brave person."
"She will do anything possible to help her little daughter," Vugrek writes in an email. "She has achieved a lot for her daughter ... She never will stop seeking for new ways to help."
HOPE AND FEAR
Kennedy is allowed only 20 grams of vegetable or fruit protein a day — no meat or dairy.
She is given two supplements: one, creatine, for her muscles; the other for her brain.
Her diet "keeps her on the brink of malnutrition, but it does control her amino acid level," says Strauss, who was authorized by McCoy to share details about Kennedy's condition.
"Dietary treatment of the disease is a precarious balance," Strauss says. "Too much protein can lead to a dangerous accumulation of methionine in the bloodstream.
"Too little protein can lead to malnutrition and all of its complications."
The supplements Kennedy takes replace some of her chemical deficiencies and keep the methionine levels within a normal range, but don't fundamentally alter the course of her disease.
"High levels of methionine can be toxic to the brain," Strauss says. "However, low levels also can arrest brain development. Thus, striking the proper balance between too much and too little protein is like walking a razor's edge."
A transplanted liver, he says, should regulate methionine levels and "correct the core problem of AdoHcy metabolism," so Kennedy no longer would need a special diet.
Strauss believes a transplant will "give her brain the best chance to develop."
The procedure has been performed successfully on more than 80 patients of the Clinic for Special Children — mostly those with Maple Syrup Urine Disease.
Kennedy would be the first person with her disorder to undergo a liver transplant.
The prospect both thrills and terrifies her mother.
McCoy keeps remembering her tiny baby in the NICU, and dreads the prospect of seeing her hospitalized again.
Kennedy needs a portion of a liver from someone unrelated to her who shares her blood type: O-positive.
When a donor is found, she will be at the Children's Hospital of Pittsburgh for several months.
Strauss says it's possible that Kennedy could continue to live with her disorder. "It depends critically on to what extent we can stave off neurological disease. Damage to the nervous system would be the ultimate determinant of both her life expectancy and her quality of life."
There's "just not a lot known about this disorder," Strauss says.
Of the seven others known to have AdoHcy, two died in early infancy. The others have significant neurological issues, Strauss says.
The liver transplant is a risk, he says, but "she's already living with a very dangerous condition. There are foreseeable dangers if she lives with this condition under current therapy."
In addition to AdoHcy, Kennedy also has a Factor VII deficiency, an inherited condition that puts her at risk of abnormal bleeding.
Strauss says liver transplantation is a "proven therapy for Factor VII deficiency."
The Clinic for Special Children sees children with rare disorders every day.
Strauss quotes a colleague, Dr. Peter Crino, a neurologist at Temple School of Medicine, who likes to say that "it's not rare if it's in the chair."
AdoHcy may be rare, but for Kennedy, it's "the most common disease in the world," Strauss says.
It's her reality, every minute of every day — and her mother's, too.
McCoy says she is comforted by the knowledge that her daughter's DNA is being studied by medical researchers on the cutting edge of science.
"My little girl's DNA has been all over the world. It's pretty incredible.
"When I have my dark times, I really just stop and think what a special purpose she has."
McCoy's favorite quote is attributed to Mark Twain: "The two most important days in your life are the day you are born, and the day you find out why."
Says McCoy: "While this is a long and treacherous road, I do believe that I was meant to walk this with Kennedy ... She is a brave little girl who is changing medicine so that other children in the future can benefit from her bravery."
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Information from: Intelligencer Journal/Lancaster New Era , http://lancasteronline.com