DNA test can solve medical riddles
KANSAS CITY, Mo. — When Kira Walker was 3 weeks old, her pediatrician noticed a problem. She was frequently hungry and had dangerously low blood sugar for no obvious reason.
Kira was born in Kansas City, Mo., where her doctors had access to a service few hospitals can match. Her DNA was sent to Children's Mercy Hospital geneticist Stephen Kingsmore, who is able to determine a diagnosis in a day or two for half the babies with mysterious diseases referred to him. Until recently, these riddles took years to solve, or were never unraveled at all.
Hundreds of babies across the United States are having large portions of their DNA deciphered as part of a five-year, federally funded project to understand and navigate the brave new world of infant genetic testing. Kingsmore and a handful of other scientists are taking gene sequencing to the next level, using the technology to design treatment for infants with rare and unusual illnesses, and in some cases, finding therapies for genetic abnormalities never seen before.
About 5 percent of all babies born in the United States — on the order of 200,000 a year — probably suffer from a rare disorder, said Michael Watson, executive director of the American College of Medical Genetics and Genomics in Bethesda, Md.
Infant genetic testing may succeed in shedding light on conditions such as progeria, the disease of premature aging that killed Sam Berns, a 17-year-old from Foxborough, Mass., who was the subject of a recent HBO documentary.
Still, many parents and doctors remain wary as health experts grapple with a myriad of issues: who will pay, how much of the information should be shared with families, and whether the procedure should only be used in sick babies. About a quarter of the parents with sick children who are eligible for free genome sequencing through his program decline it, Kingsmore said.
For those who go ahead, the benefits can be dramatic and swift.
It turns out that Kira inherited a gene mutation from her father that spurs activity in the islet cells that make insulin. However, in an unusual twist, only a portion of her cells had the mutation.
That meant that Kira's doctors could take out part of her pancreas, rather than the entire gland, an operation that would have rendered her diabetic. With half a pancreas, she continues to make insulin, and at 6 months of age, her blood sugars are now normal.
“It was such a relief,” her mother said. “It was very tense for a while there, and we had little idea of what was going on.”