What we’re missing in diagnosing autism  

The Fast Company Impact Council is an invitation-only membership community of leaders, experts, executives, and entrepreneurs who share their insights with our audience. Members pay annual dues for access to peer learning, thought leadership opportunities, events and more.

We need to change the conversation about how we diagnose autism—and what we believe causes it. 

Lately, there’s been growing attention on environmental toxins and singular external triggers as explanations for autism. But the reality is far more nuanced. As a clinical geneticist and PhD genomic scientist with over a decade of experience working in medical affairs and clinical genomics, I’ve seen firsthand how vital genetic information is in understanding autism. Many forms of autism have underlying genetic causes—and our growing ability to identify these genetic underpinnings is transforming how we diagnose, manage, and support individuals and families. 

Relying on one approach doesn’t work 

For years, autism diagnoses have relied almost entirely on behavioral assessments—observations of how a child communicates, interacts, and develops. The American Academy of Pediatrics recommends these screenings at 18 and 24 months. Yet in the U.S., the average age of diagnosis is still 5 years old. Why are families waiting years for answers when children can often be reliably diagnosed by age 2? 

The problem isn’t that we lack tools. It’s that we’ve relied too heavily on one approach. Autism is complex. Some children show mild or variable signs that are easy to overlook. Others present with overlapping developmental issues that cloud the picture. Too often, this leads to a “wait and see” approach that delays life-changing early intervention. Early intervention therapies improve a child’s communication and social skills, increase their independence in the short- and long-term, and improve their cognitive development—all crucial changes that can dramatically improve the child’s, and family’s quality of life. 

As head of medical affairs at GeneDx, I work at the intersection of clinical genomics, research, patient advocacy, and communication—and I’ve seen how genetic testing can change everything. Tools like exome and genome sequencing don’t rely on what we can observe. They uncover insights at the molecular level, giving families answers in weeks instead of years. That kind of clarity can make a profound difference in a child’s care and development. 

Genetic testing 

Genetic testing is not hypothetical—it’s happening now, and it’s effective. Over 800 genes have been linked to autism spectrum disorder, and that number continues to grow. Exome sequencing looks at the portions of the genome that tell our bodies how to make proteins, while genome sequencing captures even more data by examining all of a person’s DNA. When a change, or variant, is found in a child’s DNA with one of these tests, it can explain the underlying cause of their developmental differences. These tests can yield a genetic diagnosis in up to 36% of children who show symptoms of autism alongside other developmental concerns. Just 10 years ago, these tests cost tens of thousands of dollars and took months to return results, but now, thanks to innovation and investment, patients can access these tests through most national insurance plans and can receive results in weeks, if not days.  

A genetic diagnosis is more than a label. It can unlock access to targeted therapies, inform medical management, provide eligibility for clinical trials, help families better understand what to expect, and help families connect with other families who have the same diagnosis. In many cases, it can alleviate the emotional weight of uncertainty—offering not only answers, but also a path forward. 

Genomics should be a standard in healthcare 

My career has been driven by the belief that genomic information should be a standard part of healthcare—especially for individuals with rare and complex conditions like autism. Before joining GeneDx, I led clinical genomics teams, built testing programs with biopharma partners, and supported technologies to improve the accuracy and accessibility of genetic testing. Across every initiative, one thing has remained clear: The earlier we integrate genomic data into care, the more informed and effective that care becomes. 

This Autism Acceptance Month, I encourage families, pediatricians, and policymakers alike to consider how far we’ve come—and how far we still need to go. We must move beyond narrow narratives and singular explanations. We must embrace the complexity of autism, and the role genetics plays in it. 

We owe families more than vague guesses and delayed answers. With the tools we have today, we can provide answers sooner—and that’s a change worth making. 

Britt Johnson, PhD, FACMG is head of medical affairs at GeneDx. 

View the full article