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PubMed This is a summary of 23 peer-reviewed journal articles Updated
Medical Genetics · Maturity-Onset Diabetes of the Young

What Does a VUS Mean on Your MODY Genetic Test Results?

At a Glance

A variant of uncertain significance (VUS) on a MODY genetic test means a DNA change was found, but there is not enough evidence to tell whether it causes diabetes. It neither confirms nor rules out MODY and should not independently change treatment or relatives’ medical care.

Receiving your genetic test results and seeing “Variant of Uncertain Significance” (VUS) can be frustrating and anxiety-inducing. It is completely normal to feel let down by an unclear result.

To answer your question directly: a VUS neither confirms nor rules out MODY [1][2]. It is an inconclusive result. It means the laboratory found a change in your DNA sequence, but there is currently not enough scientific evidence to know whether this change causes Maturity-Onset Diabetes of the Young (MODY) or if it is just a normal, harmless genetic difference [3][2].

Because MODY is actually a group of different genetic forms of diabetes (not just one single condition), a VUS in a MODY-associated gene is not the same as a clinical diagnosis of a specific MODY subtype [4][5].

What is a Variant of Uncertain Significance?

When geneticists analyze your DNA, they evaluate various types of evidence—such as population databases, computational models, and family history—to categorize any DNA changes they find into one of five categories: benign (harmless), likely benign, uncertain significance (VUS), likely pathogenic (disease-causing), or pathogenic [1][6].

A VUS means the available evidence is currently insufficient or conflicting [1]. The laboratory simply cannot determine yet whether the DNA change affects your health [2]. Because we all have natural variations in our genes that make us unique without causing disease, a VUS cannot be treated as a definitive diagnosis.

What Does This Mean for Your Treatment?

Because a VUS is not a confirmed diagnosis, it should not be used on its own to change your medical care [7][2]. For example, if you are currently taking insulin, you should not stop taking it or change your medications just because a VUS was found in a MODY-related gene [8][2].

While your clinician might eventually revise your diagnosis or treatment based on your overall clinical picture, your management should remain based on your symptoms and blood sugar control, rather than this uncertain genetic result [7].

Next Steps: Clinical Correlation

When you get a VUS, the next step is usually a clinical correlation, which means looking at the bigger picture of your health to see if a clinical diagnosis of monogenic diabetes still makes sense. No single finding proves or disproves MODY, but your care team will evaluate:

  • Your specific symptoms: They will look at your age at diagnosis, your body mass index (BMI), and specific blood tests like C-peptide (a marker of how much insulin your pancreas is making) and islet autoantibodies (immune markers that typically point to Type 1 diabetes) [9][10]. Keep in mind that having autoantibodies does not absolutely rule out MODY, but it is an important clue [11].
  • Your glycemic pattern: How your blood sugar behaves and responds to certain treatments can offer clues [12].
  • Family History: A strong, multi-generational history of diabetes can support a MODY diagnosis, though lacking one does not rule it out [4].
  • Extra-pancreatic features (features outside the pancreas): Some specific genes linked to MODY also cause other issues, like kidney cysts (in the HNF1B gene) or hearing loss [13][14].

The Role of Family Testing

For a known disease-causing variant, doctors often recommend routine predictive testing for family members. However, for a VUS, testing relatives is a specialized process called segregation testing [15][16]. This is a way to gather evidence for the laboratory by seeing if the DNA change tracks with diabetes across your family tree [15][17].

Segregation testing should only be done when your genetics team believes it will be informative [16]. Finding the variant in affected relatives does not automatically prove it causes diabetes [18]. Likewise, an unaffected relative might have the variant but simply hasn’t developed diabetes yet—a concept known as reduced penetrance [19][20]. Relatives’ medical care should never be changed based on a VUS.

Will the VUS Ever Be Resolved?

Reclassification is possible as scientific databases grow, but it is not guaranteed. In one specific research study of patients with unresolved MODY variants, about 43% of the VUS results were successfully reclassified after a median of 8 years (mostly to benign/likely benign, and occasionally to pathogenic/likely pathogenic) [21].

However, reclassification rates vary widely depending on the gene and the laboratory. There is no universal schedule for when labs re-evaluate these variants [22][23].

What you can do:

  • Keep a copy of your full laboratory report.
  • Ask your genetic counselor or testing lab about their specific policy for re-evaluating variants and issuing amended reports [22].
  • Ensure your genetics clinic has your up-to-date contact information so they can reach you if the classification changes.

Summary: What a VUS Does and Doesn’t Do

  • Does: Tell you that a genetic change was found, but its health impact is unknown.
  • Does not: Confirm that you have MODY.
  • Does not: Rule out MODY.
  • Does not: Provide a reason to stop taking insulin or change your diabetes medication on its own.
  • Does not: Provide a definitive risk result for your family members.

Common questions in this guide

What does a VUS mean on a MODY genetic test?
A VUS means the laboratory found a change in your DNA, but current evidence is not strong or consistent enough to show whether it causes MODY. It is an inconclusive finding, not a confirmed diagnosis.
Does a VUS confirm or rule out MODY?
No. A VUS neither confirms nor rules out MODY because it may represent a harmless genetic difference or a disease-causing change that has not yet been established. Your clinical findings and diabetes history still guide evaluation.
Should I stop insulin or change diabetes medicine because of a VUS?
No, do not stop insulin or change diabetes medicines based on a VUS alone. Treatment should be guided by your blood sugar control, symptoms, and overall clinical assessment, together with advice from your healthcare team.
How do doctors interpret a VUS when evaluating possible MODY?
Doctors compare the result with your age at diagnosis, body mass index, C-peptide, islet autoantibody results, blood sugar pattern, and family history. They may also look for features associated with some MODY-related genes, such as kidney cysts or hearing loss. This broader review is called clinical correlation.
Should my relatives be tested for a MODY VUS?
Relatives should not be tested automatically, but a genetics team may recommend specialized segregation testing when it is likely to clarify the result. Finding the VUS in relatives with diabetes does not by itself prove that it causes diabetes, and family members' care should not change based on the VUS.
Can a VUS on a MODY test be reclassified later?
Yes, a laboratory may reclassify a VUS as more evidence becomes available, but reclassification is not guaranteed and there is no universal timeline. Keep your report and contact information current, and ask the testing lab how it handles amended results.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What exact gene and genetic variant (VUS) was found on my report?
  2. 2.Based on my symptoms, C-peptide levels, and autoantibody tests, how strongly do you still suspect a clinical diagnosis of MODY?
  3. 3.Do you recommend specialized family testing (segregation testing) to help clarify this result, and if so, which relatives would be most informative?
  4. 4.What is the testing laboratory's policy on re-evaluating VUS results, and how will we be notified if my variant is reclassified?
  5. 5.Does this uncertain result change anything about my current diabetes management or medications?

Questions For You

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Related questions

Can C-Peptide Suggest MODY After Years of Diabetes?What Is the Difference Between MODY and Type 1 Diabetes?Will My Health Insurance Pay for MODY Genetic Testing?How Is Fetal Growth Monitored in GCK-MODY Pregnancy?How Is the Gliclazide Challenge Test Used for MODY?Can I Take Ozempic or Jardiance for MODY Treatment?Why Does HNF1B-MODY Affect the Kidneys? Cysts & CKDWhat Is the Long-Term Complication Risk in MODY Diabetes?Could MODY Cause Low Blood Sugar in My Baby at Birth?What Do CEL, BLK, ABCC8, and KCNJ11 Results Mean in MODY?Should Family Members Get Genetic Testing for MODY?Can You Switch Insulin to Sulfonylureas Safely in MODY?Should I Switch Sulfonylureas to Insulin in MODY Pregnancy?How Does the GCK-MODY Reset Thermostat Mechanism Work?Why Is MODY Misdiagnosed as Type 1 or Type 2 Diabetes?Will I Need Insulin Again for MODY in the Future, and When?

References

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This page is for informational purposes only and does not constitute medical advice. Your genetics team and diabetes clinician should interpret your MODY VUS and guide treatment decisions.

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