For most of my career, diagnosing complex gastrointestinal conditions meant piecing together symptoms, running labs, ordering scopes, and relying on clinical judgment built over years of practice. That still holds true. But something has shifted in the last few years — and it’s changing what “thorough” means in gastroenterology.
Genetic and genomic testing is no longer just for oncology departments or rare disease specialists. It’s becoming a practical tool for GI clinicians managing everything from inflammatory bowel disease to hereditary colorectal cancer risk to treatment-resistant IBS.
The challenge is that most gastroenterologists weren’t trained to interpret genomic data. And the gap between ordering a test and actually understanding what comes back is wider than most people realize.
The GI Conditions Where Genomics Now Matters
Let’s be specific. This isn’t about genomics as a vague future trend. There are concrete clinical scenarios where genetic and NGS-based testing is already changing patient care in gastroenterology:
Hereditary colorectal cancer syndromes — Lynch syndrome, familial adenomatous polyposis (FAP), MUTYH-associated polyposis. These are conditions where identifying pathogenic variants in genes like MLH1, MSH2, APC, or MUTYH directly changes surveillance protocols, surgical decisions, and cascade testing for family members. A patient who presents with early-onset colorectal cancer or a strong family history deserves more than a colonoscopy and a referral. They deserve a clear answer.
Inflammatory bowel disease — IBD has a complex genetic architecture. While we’re not at a point of diagnosing Crohn’s or UC by genotype alone, genetic testing is increasingly relevant for understanding disease risk, guiding biologic selection, and identifying rare monogenic forms of very early onset IBD in pediatric patients that present similarly to classic IBD but require entirely different management.
Pharmacogenomics for GI drugs — Thiopurine metabolism is the classic example. TPMT and NUDT15 variants predict who will develop life-threatening myelosuppression on azathioprine or 6-mercaptopurine. Testing before prescribing is no longer a niche consideration — it’s increasingly standard of care, and FDA labeling for these drugs reflects that.
Celiac disease and HLA typing — HLA-DQ2 and HLA-DQ8 testing has a useful negative predictive value. A patient who tests negative can effectively be ruled out for celiac disease, which matters a lot when you’re trying to avoid unnecessary long-term dietary restriction.
The Interpretation Problem
Ordering the test is the easy part. What comes back is often the hard part.
A next-generation sequencing panel for hereditary GI cancer risk might return a pathogenic variant, a likely pathogenic variant, a variant of uncertain significance (VUS), or a negative result — each of which has a completely different clinical meaning and a different action required. Getting a VUS back and not knowing what to do with it is unfortunately common. Patients get confused. Families get alarmed. Clinicians get stuck.
This is where the infrastructure behind genetic testing matters as much as the test itself. The difference between a result that’s actionable and one that creates more questions than it answers often comes down to how that variant was classified, what evidence was used, and whether the interpretation followed a structured framework.
The field has moved toward the ACMG/AMP variant classification guidelines as the standard framework — pathogenic, likely pathogenic, VUS, likely benign, benign — and clinical-grade variant interpretation software built on this framework is what allows labs and clinicians to actually apply it consistently at scale.
For gastroenterologists who want to engage with this space rather than simply defer everything to genetics departments, understanding what clinical genomics software does — and how it produces the interpretations you’re reading — is genuinely useful. Tools like those offered by Golden Helix are designed specifically for this kind of structured variant interpretation, applying evidence-based classification frameworks to variants identified through NGS panels so that the output is clinically usable rather than just data.
What This Means for Clinical Practice
Gastroenterology is not going to become a genomics specialty overnight. Most GI clinicians don’t need to become bioinformaticians. But a few things are worth internalizing:
Know when to test. Early-onset colorectal cancer, strong family history, suspected hereditary syndrome, IBD in a pediatric patient, or a patient about to start thiopurines — these are scenarios where genetic testing changes management, not just adds information.
Know how to read what comes back. Classification terminology matters. A “variant of uncertain significance” is not a diagnosis. A “likely pathogenic” variant may still require confirmatory testing. Understanding the difference between these categories saves patients from inappropriate over- or under-treatment.
Build the right referral pathways. Genetic counselors are underutilized in gastroenterology. Having a relationship with a certified genetic counselor who understands GI conditions means your patients can actually process what their results mean — and make informed decisions about surveillance, surgery, and family testing.
Don’t treat genomics as a tiebreaker. Genetic results don’t replace clinical judgment. A negative genetic panel doesn’t rule out hereditary risk if the clinical picture is compelling. A pathogenic variant doesn’t automatically mandate the most aggressive intervention. Genomics adds a layer of information — it doesn’t override everything else you know about the patient.
The Integration Is Already Happening
For the GI clinician who has been watching this space from a distance, the window to engage proactively is now. Genomic testing is getting cheaper, faster, and more accessible. Patient awareness is increasing — people are coming in having done direct-to-consumer genetic tests, wanting to know what their results mean for their GI health. The infrastructure for interpreting results — annotation databases, variant classification frameworks, clinical decision support — is maturing.
Gastroenterology has always been a specialty that integrates technology well. We adopted endoscopy, capsule endoscopy, and advanced imaging into standard practice because the clinical value was clear. Genomics is next — not as a replacement for anything, but as an additional lens for patients who need more than a scope and a symptom checklist can give them.
The patients who benefit most are the ones we currently serve least well: the ones with atypical presentations, the ones with strong family histories we can’t fully explain, the ones who cycle through treatments without durable response. For those patients, genomics isn’t academic. It’s the answer we’ve been missing.
