Getting a diagnosis of Pompe disease can be difficult. This is partly because the disorder is so rare. It affects only about 1 in 40,000 people in the United States.

“It’s really not on the radar of most pediatricians,” says Gerard Vockley, MD, PhD, chief of genetic and genomic medicine at UPMC Children’s Hospital in Pittsburgh.

Another reason is that some of the symptoms of Pompe disease, such as muscle weakness and breathing problems, are also signs of other, more common conditions. The condition is different in each one. And symptoms can appear at any age, from childhood to adulthood.

Advances in newborn screening have made it easier to diagnose babies, including those with less severe forms of the disease. That means more babies receive life-saving treatment right away.

But some people with Pompe disease embark on a diagnostic odyssey that takes years, says Christina Grant, MD, PhD, co-director of the Lysosomal Storage and Treatment Program at Children’s National Hospital in Washington, DC. Some research suggests

When a baby is born, a neonatal screening panel is performed using blood collected with a heel stick. The conditions for which newborns are routinely screened vary from state to state. According to Pompe Disease News, at least 20 states, including New York, Massachusetts and California, now screen for Pompe disease.

Your pediatrician or the state screening program may contact you if your baby’s results were outside the normal range. That doesn’t necessarily mean your baby has the condition. There could be another reason, such as the blood sample being too small. You will see a pediatric geneticist, who will perform more blood tests to confirm if your baby has the condition.

Before giving birth, it’s a good idea to check if your state includes Pompe disease in its newborn screenings, Vockley says. Otherwise, ask the hospital if they can perform the test anyway.

“It is an important diagnosis, because it is one of the few diseases that can be diagnosed at birth and for which immediate treatment is available,” he says.

Even if your baby tests positive for Pompe disease, that doesn’t necessarily mean he or she has a severe form of the disease. “Some of these children will not develop symptoms much later in life, and some will be so mild that they otherwise would never have been diagnosed,” Grant says.

If your baby tests positive on the newborn screening test but shows no signs of heart, muscle, or other organ damage, he or she may simply need to be monitored closely, she says.

If you know that Pompe disease runs in your family, you can have prenatal testing before your baby is born. Your doctor takes a sample of amniotic fluid (the fluid that surrounds the baby in the womb) or placenta (the organ that provides nutrients to the fetus) for genetic testing.

If your baby is not tested for Pompe disease as part of his or her newborn screening, he or she may be diagnosed after you notice something is wrong.

Doctors can detect muscle weakness right away in a newborn with a severe case. “But pediatricians may miss other babies with mild to moderate symptoms, who take more of a ‘watch and wait’ attitude when it comes to their muscle tone,” Vockley says.

These are warning signs during a baby’s first year of life:

• Not gaining weight and growing.
• feeding problems
• Poor muscle tone
• Respiratory problems
• Large and protruding tongue
• The legs usually rest in a “frog” position.
• Frequent respiratory infections
• An enlarged liver
• listening to problems
• Delayed motor skills, such as rolling over and sitting up

Late-onset Pompe disease tends to be milder. It can appear during childhood or in adults of any age. Warning signs include:

• Muscle weakness, especially around the torso, shoulders and legs.
• Respiratory problems
• Bad balance
• a curved column
• Chewing and swallowing problems.
• Drooping upper eyelids.

If you or your child have symptoms like these, your doctor will perform a thorough examination and obtain a detailed health and family history. They will try to rule out other more common conditions.

If your doctor suspects that you or your child may have Pompe disease, you may have several types of tests. The most common tests the activity of an enzyme called acid alpha-glucosidase. This is the same test used for newborn screening. It can be done as a blood test or as a skin biopsy, in which a small sample of skin is taken for analysis.

You or your child may also undergo genetic testing, which looks for mutations in the gene that controls this enzyme, to confirm the diagnosis. Genetic testing also identifies people who carry the disease, even if they never get it. It is done with a blood or saliva sample.

Your doctor may also do other tests to see what problems Pompe disease may be causing. They could include:

Cardiac tests. This might include a chest x-ray to check the size of the heart, as well as an echocardiogram or cardiac ultrasound to look for thickening of the heart walls.

Breathing tests. These measure lung capacity, which can affect Pompe disease.

Muscle tests. This could include an electromyogram, which detects problems with muscle function, and an MRI to detect muscle damage.

Sleep studies. These look for breathing problems that occur during sleep.

Depending on the test results and the severity of your symptoms, your doctor may recommend starting enzyme replacement therapy (ERT) immediately. Pompe disease can affect many parts of your body. Therefore, treatment may also include care from a team of specialists, including:

• Metabolic specialists
• Neurologists
• Cardiologists
• Pulmonologists
• orthopedists
• Physical, occupational and speech therapists.

Experts suspect that some people who test genetically positive for Pompe disease never show signs of illness.

“We are now seeing women who were referred to us during their pregnancy who never developed symptoms but tested positive for the disease,” Grant says. “Although we confirmed that they have the disease with genetic testing, they do not have any of the abnormal blood or muscle tests associated with the disease.”

These women have blood tests every year to look for changes that would require them to start ERT, she says.

“It’s reassuring for pediatric and adult patients to know this, so they don’t feel like a Pompe disease diagnosis is a death sentence,” Grant says.