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Newborns Could Soon Be Screened for Rare “Pompe” Enzyme Deficiency Disorder

Screening for this disorder could save lives, but also prompts hard choices for parents and physicians



Jensflorian

Shortly after a baby’s first wail at birth she or he receives a tiny prick on the heel. A few drops of blood are caught on special filter paper to screen for myriad diseases.

Across the U.S. almost 30 standard tests for medical conditions in infants rely on sampling from those blood spots. Now the Department of Health and Human Services (HHS) is considering adding another disease to its list of recommended newborn screenings. A federal panel this spring recommended that the rare, and often fatal, Pompe disease be added to the mix, causing HHS Secretary Kathleen Sebelius to mull her options.

This inherited enzyme deficiency disorder, named for Dutch physician Johannes C. Pompe who first described it in 1932, is caused by the buildup of glycogen in the body’s cells. If detected early, doctors can start enzyme replacement therapy, a costly regimen of biweekly infusions that add a missing enzyme, acid alpha-glucosidase (GAA), back into the body. The four-to-six-hour infusions must be continued for life. The procedure reduces sugar accumulation, and is designed to help stave off muscle degradation and heart defects. People with this disease have mutations in a particular gene that usually serves as the instruction manual for how to produce GAA. That enzyme normally breaks down glycogen into glucose, a vital energy source for most cells. Without effective breakdown of glycogen the sugar can build up to toxic levels within cells, in turn damaging muscles and other organs and tissues. Pompe disease occurs in one in 28,000 people.

Typically, untreated infants with an early-onset form of the disease die of cardiac failure before age one. The enzyme replacement therapy—available since 2006—saves lives, but children may still end up on ventilators later in life. Long-term outcomes for patients receiving treatment are not well known, but researchers estimate that national screening could avert an estimated 13 deaths and 26 cases of ventilated babies per year.

Screening might force parents and doctors to grapple with uncertainties about when to initiate therapy because the initial test also reveals whether a late-onset form of Pompe disease may develop. Whereas the early-onset form of the disease is rare—only one in 100,000 infants have it—the later-onset form makes up about 72 percent of all cases. And late-onset Pompe disease is a bit of a wild card: its symptoms might not show up until adulthood, but they could manifest as early as age eight—or even before. Enzyme replacement therapy can cost more than $100,000 annually for a small child’s infusions, but delayed therapy might result in irreversible muscle damage. The cost increases as the child gets bigger as the infusion amount depends on size. Barry Byrne, a pediatrician at the University of Florida who helped advise the federal panel that recommended adding Pompe disease to the standard tests for newborns, says physicians still have few definitive answers about Pompe disease treatment because there is little research on it. A positive result for late-onset Pompe disease typically prompts doctors and families to keep a close watch for symptoms of the disease, such as muscle weakness, to know when to start therapy. Adding the test to the national list of recommended newborn screenings is vital, Byrne says, because “one of the purposes of screening is to avoid delayed diagnosis and detect cases that go unrecognized.”

In Missouri a statewide pilot-screening program for Pompe disease costs approximately $1 per screening, according to that state’s Department of Health and Senior Services. U.S. HHS has not yet said when it plans to issue a decision on the national recommendations, and declined to comment further for this story. If the disease does make the recommended screenings list, however, it will be up to state governments to decide if and when to begin testing.

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