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Changing Lives Through DNA Genetic Testing
The AGS Blog & Press Releases

Dreading Dairy - The MCM6 Gene and Lactose Intolerance and DNA Genetic Testing

[fa icon="calendar"] Jul 17, 2017 7:55:06 AM / by Catherine Levesque

Catherine Levesque

Ah, July. A time for celebration, relaxation, and of course, indulging in the quintessential summer treat - ice cream. For many of us, just thinking about the frozen dessert makes our mouth water. For others, it evokes memories of upset stomachs and sprints to the bathroom. But why is it that some of us have such adverse reactions to this dairy product, while others are fine?

lactose-intolerance-get-a-DNA-testWhen you were growing up, weren't you constantly told to drink your milk? Interestingly enough, 65% of us are unable to properly breakdown these milk sugars. That number jumps to a staggering 90% in some areas of East Asia. If you’ve experienced any of the following symptoms after ingesting milk, cheese, or yogurt, there’s a good chance you too have trouble with dairy:

  • Abdominal Pain
  • Bloating
  • Cramping
  • Diarrhea
  • Nausea
  • Vomiting


To better understand why these symptoms occur, we must examine two genes: LCT and MCM6.


The LCT gene is responsible for manufacturing lactase, an enzyme essential for breaking down the lactose sugar contained in dairy products. As we progress from infancy to adulthood, we no longer rely on breast milk as a nutrient source. Decreased expression of the LCT gene with age is thus common in humans, as our body avoids expending energy producing enzymes that are no longer vital. After all, if you don’t use it, you lose it.



AGS-MCM6 Gene Image.png

Located inside the long arm of chromosome 2, MCM6 gene plays a governing role in our ability to metabolize milk products. A specific portion of the MCM6 gene, known as a regulatory element, modifies the expression of the nearby LCT gene, and thus the production of lactase.

Let me walk you through how MCM6 works...Though our body is mostly accurate when replicating our DNA, sometimes it makes mistakes. There are at least 4 single nucleotide polymorphisms (copying errors) within the MCM6 gene that affect LCT expression. Though this may sound like a bad thing, it’s actually the exact opposite. All 4 of these SNPs enable a person to have sustained lactase production into adulthood. In other words, these tiny mutations actually benefit the individual, allowing them to consume dairy without the uncomfortable symptoms. People who do not possess such SNPs gradually lose the ability to break down milk sugar as they age due to stunted lactase production, and are considered lactose intolerant.

Want to know if you are able to digest lactose? Or if you should start cutting dairy products out of your diet today?


Click the button below to learn about our AGS Health and Wellness genetic test, which examines MCM6 and over 50 other genes.


Learn More

Topics: Genetic Testing 101, Lactose Intolerance

Catherine Levesque

Written by Catherine Levesque

Catherine attending New York University as a Biology major. She aspires to be a pediatric oncologist, and is excited to see how pharmacogenetics revolutionizes the field of cancer treatment.

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