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Genetic mutation analysis for LCT gene (Lactase)

Published: August 9, 2026Updated: August 16, 2026

This test checks for mutations in the LCT gene, which affects lactase production. Lactase is an enzyme needed to digest lactose, a sugar found in milk and dairy products.

Quick summary

["Helps determine if you may have lactose intolerance due to genetic differences."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
58938-2
Short code
LCT gene Mut Anl Bld/T
Synonyms
LCT gene Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Does This Test Measure?

The LCT gene mutation test looks for changes (mutations) in the DNA sequence of the LCT gene. These mutations can prevent your body from making enough lactase, which can lead to lactose intolerance. The test is often done if you experience symptoms like bloating, gas, or diarrhea after consuming dairy products.

Why Might You Need This Test?

Your healthcare provider may recommend this test if you have symptoms like digestive issues after eating dairy, even if you don’t suspect lactose intolerance. It can also be part of genetic counseling for families with a history of lactose intolerance or related conditions.

How Is the Test Performed?

The test typically involves collecting a small amount of blood or saliva. Blood samples are often sent to a lab for genetic analysis, while saliva samples may be analyzed directly. The lab will examine the LCT gene for specific mutations that could affect lactase function.

What Are Possible Results?

Results can indicate whether you have certain known mutations in the LCT gene. Some mutations may lead to lactose intolerance, while others might not cause symptoms. Your results will be interpreted by a healthcare provider based on your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Mutations in the LCT gene can cause lactose intolerance, which means your body struggles to digest lactose properly. This can lead to digestive discomfort, including bloating, gas, diarrhea, or stomach pain after consuming dairy products. Identifying these mutations helps tailor dietary advice and manage symptoms effectively.

Short name

LCT Gene Mutation Test

Frequently asked questions

What does a positive result mean?
A positive result means that you have certain mutations in the LCT gene that may contribute to lactose intolerance. However, not all mutations cause symptoms, and some people with these mutations may still tolerate some dairy. Your healthcare provider will discuss how these results might affect your diet and overall health.
Can I still eat dairy if I have these mutations?
Yes, but it depends on the type and severity of the mutations. Some people with LCT gene mutations can still consume small amounts of dairy without issues, while others may need to avoid it entirely. Lactose-free products or gradual reduction in dairy intake can sometimes help manage symptoms.
How often should I get this test?
This test is usually done once if you suspect lactose intolerance based on symptoms or family history. If you have a genetic predisposition or specific symptoms, your healthcare provider may recommend follow-up testing or monitoring. It’s not typically a routine screening test unless advised otherwise.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy