What genetic testing can (and can’t) do

As a pediatrician who treats children with medically complex conditions, I’m often asked questions about genetic testing. 

It’s only natural for parents of younger children to want to know more about a child’s possible developmental delays, or physical or cognitive differences. 

And sometimes genetic testing can offer that clarity. 

I tell parents, however, that realistic expectations are important. And I urge them to recognize what genetic testing can do for your child and your family — but also what it can’t. 

Indeed, part of my role as a complex-care pediatrician is helping families understand the advantages and limitations of genetic testing.

Finding the right specialist 

A trained medical professional, ideally a neurologist or geneticist, should order and interpret genetic test results. Results can be complex, and they’re often inconclusive. You need a highly proficient provider who can clearly interpret results that may involve a lot of gray area. 

I also encourage families to explore other valuable diagnostic tools, such as imaging tests and developmental screenings by trained pediatric specialists. A comprehensive evaluation is important because not every complex condition has an underlying genetic cause. 

Cerebral palsy, for example, is caused by damage to the brain before, during or shortly after birth, so it isn’t something a genetic test alone would pick up on.

Results aren’t always clear 

Genetic testing can be valuable in confirming a suspected diagnosis — for instance, when a child has physical characteristics suggestive of a certain medical condition. 

Christy Lawler of Fargo, N.D., learned her infant son, Dalen, had achondroplasia, a form of dwarfism, after a blood test. They had suspected the diagnosis because of his appearance, but knowing for certain gave Christy and Dalen’s doctors a clearer idea of the treatments he would need as he grew. 

On the flip side, testing doesn’t always yield a clear answer. That’s because many chromosome deletions or duplications don’t have a formal name — more often than not, you can’t put the diagnosis into a bucket. 

Opportunities and limitations 

We don’t always know how — or if — a diagnosis might change the course of a child’s life.  

And that uncertainty can be difficult for families. Difficult, too, is the fact that chromosome duplications or deletions can be discovered, but not necessarily repaired or “cured.” 

Even when test results give us a “why,” it doesn’t mean we can change a condition’s course. We can, however, start interventions — things like treatments and therapies — early, to keep a child as healthy as possible. 

Anna and Jared Bird of Cottage Grove, for example, began physical and speech therapy for their son, Elliot, who has a rare chromosomal abnormality, before he turned 2. He also underwent surgeries to correct his cleft lip and palate and tethered spinal cord. 

Today, Elliot is a happy 8-year-old who loves exploring the outdoors. He continues to receive occupational and speech therapy.

Knowledge is power 

Results of genetic testing can also shed light on things to watch for in the years ahead. 

If a certain syndrome or gene duplication is associated with a specific health issue, such as kidney problems or seizures, a child can be regularly assessed by a specialist in that area. 

That’s useful in terms of helping us better understand the child and make health decisions.  

Formal name or not, confirmation of a genetic abnormality can answer that elusive question of, “Why?”  

Knowledge is power, so the more you can know about your child, the better. I think parents also can benefit psychologically when there’s something concrete to explain a child’s situation. 

When a child’s syndrome or condition is confirmed, another big question often arises: What is the likelihood that future siblings will share the diagnosis?

The answer isn’t necessarily black and white. Some conditions are carried in one or both partners’ genetic code, while others occur spontaneously. 

I advise families to seek out a genetic counselor, who can recommend the right tests and offer support.


Dr. Madeleine Gagnon is a complex-care pediatrician at Gillette Children’s Specialty Healthcare in St. Paul.