Liver transplants giving children with a rare disease 'a new life'
New approach is taken to treat metabolic disorder
WASHINGTON -- Liver transplants seem to be curing about a dozen children of a rare disease so unforgiving that the slightest dietary misstep can prove brain-damaging or fatal.
Now instead of a life of fear with every bite of a strict low- protein diet, patients with maple syrup urine disease eat ice cream, hamburgers, and other normal children's fare.
And doctors are studying whether the transplants help children who have had some brain damage get a little better in addition to averting problems.
''Subjectively, we're noting things like improved attention span, better speech, areas we are thrilled that are occurring," said Dr. George Mazariegos of Children's Hospital of Pittsburgh. He is about to publish in a medical journal the first results of this new approach to treating the genetic disease.
As his first patient's mother, Susan Jasin of Alpharetta, Ga., put it: ''It's a new life for us." Her son Jakob, now 5, underwent the transplant in May 2004.
Maple syrup urine disease, named for the telltale symptom of sweet-smelling urine, occurs in about 1 in 225,000 births. Patients' bodies can't process three amino acids found in protein -- leucine, isoleucine, and valine. Those amino acids can build up to toxic levels, causing mental retardation, physical disabilities from neurologic damage, and even death.
To survive, patients are put on a lifelong diet that is super-low in protein; many patients' primary nourishment is a special liquid formula. Because some protein is in most foods, restrictions on other fare go beyond no meat or dairy products. Jakob, for instance, liked potatoes so his mother carried a scale to measure the handful of french fries his body could tolerate.
Diet aside, even a minor illness that causes children not to eat on schedule can send them into seizures as their bodies break down stored protein.
Improved newborn screening is allowing treatment to start earlier, saving lives. But few patients reach adulthood without some neurologic delay or worse, said Mazariegos, who described his team's first 13 transplants at a recent pediatricians' meeting.
All the patients began eating a regular diet within days of surgery, and their bodies are normally processing protein, Mazariegos reported. Five had mild symptoms of organ rejection, controlled with medication.
Any age after 1 seems OK to operate, he says. The median age of his patients is 6; the youngest was 1 1/2 and the oldest 20.
That a transplant might help was a surprise, discovered when an 8-year-old with the illness received one after a vitamin A overdose destroyed her liver. Her amino acid levels normalized within hours of the 1997 transplant, and she's been fine since.
A new liver doesn't get rid of the genetic defect, but it seems to carry enough of a protein-digesting enzyme to counter the defect.