HOW NEWBORN SCREENING TESTS COULD CHANGE
BY MARIE MCCULLOUGH
PHILADELPHIA - Editor's note: The Eagle recently carried a report about newborn screening tests.
Wendy Nawn began crusading to expand newborn health screening after she saw what happened to her son Alex, who inherited a rare metabolic disorder that can cause brain damage and death.
What happened was wonderful.
An analysis of a few drops of blood taken from Alex's heel soon after birth revealed his faulty gene. An endocrine nurse told his parents that he could not go more than five waking hours without eating because his body cannot break down fat. Today, almost six years later, both Alex and his little brother, who also has the little-known disease, are as healthy as they are precocious.
Most children with medium-chain acyl-CoA dehydrogenase deficiency, or MCAD deficiency, are not so fortunate, Nawn said.
"I cannot tell you how fuming we would be if this had happened to Alex," she said, "and if we had later learned there is an inexpensive test to detect this silent disease presymptomatically."
The damaging effects of many diseases can be prevented or reduced through early intervention with tailored diets and, in some cases, drugs. Yet 40 years after the first screening test was developed, detection programs vary wildly. Pennsylvania mandates screening for six diseases, Kansas for four, other states for 30 or more.
Nawn's advocacy group, Save Babies Through Screening, is in the forefront of a parent-driven movement to get every state to screen newborns for an evolving list that now includes more than 50 rare metabolic illnesses.
While there is continuing debate about checking for metabolic diseases that cannot be effectively treated, a federal initiative may finally turn the nation's screening crazy quilt into some sort of blanket protection.
A federal advisory committee on newborn screening last year recommend testing all babies for about 30 genetic disorders using the latest rapid-detection technology. The Maternal and Child Health Bureau just finished taking public comments on the report.
The first newborn screening test was developed in 1961 for phenylketonuria, or PKU, an enzyme abnormality that, without dietary management, causes mental retardation, dangerous blood clots and liver failure.
Now, nearly all states screen for PKU and three other disorders.
But by the early 1990s, screening was becoming a complex issue. More and more disorders were identified as scientists found ever-subtler defects in genes that regulate the body's metabolism of proteins and enzymes. An ultra-fast analytical instrument called tandem mass spectrometry enabled screening a blood sample for dozens of molecular disease markers in a matter of minutes.
The problem is that a tandem mass machine can cost as much as $500,000 (plus the staff to run it), and there are no effective treatments for some of the disorders it can detect. Some experts estimate that hundreds more metabolic genetic defects that fall into this gray area may be identified.
There are other dilemmas, as Thomas Jefferson University pediatrician Gary Emmett writes in a new pediatrics textbook. Some congenital metabolic defects -- such as alpha1-antitrypsin deficiency, which can cause lung and liver damage -- are expensive to screen for. Other disorders -- such as arginase deficiency, which can cause quadriplegia, retardation and seizures -- have been diagnosed in so few patients that it is not yet clear whether treatment works.
Screening also "opens up a Pandora's box of difficult ethics and privacy questions," Emmett writes. States must figure out "how much we should know about each individual's genetic makeup, and who is allowed access to that knowledge."
No wonder screening programs across the country have become increasingly inconsistent, despite calls for a more orderly system from the American Academy of Pediatrics, the March of Dimes and the Council of Regional Networks for Genetic Services.
Some states have argued that inherited metabolic diseases are so uncommon, parents who want extra screening tests should pay out of pocket -- $25 to $90 -- to one of the nation's four commercial newborn-screening labs.
But because the diseases are uncommon -- altogether, about 4,000 of the 4 million babies born each year are affected -- few parents know about supplemental screening unless doctors inform them.
Families who learn about these horrible disorders, sometimes too late to save their children, have pressured state legislatures and hospitals to expand screening.
If the federal advisory committee recommends national screening for 30 disorders, it may force all states to accept this as the minimum "standard of care," experts say.
The 30 disorders were selected by a team of doctors from the American College of Medical Genetics, said Mike Watson, executive director of the college and head of the team. The team analyzed 84 rare diseases, Watson said, but chose only those that met key criteria, including: the screening test is reliable; the disorder causes serious harm and has an effective treatment; and intervention at birth is better than after symptoms
Courtesy of Saving Babies Through Screening Foundation