LCT rs4988235: Understanding Lactase Persistence Genetics
The rs4988235 variant is a well-studied genetic marker located near the LCT gene that influences the production of the enzyme lactase in adults. It is strongly associated with the trait of lactase persistence, which determines an individual's ability to digest lactose found in dairy products.
What each genotype means
Lactase non-persistence
This genotype is associated with a reduced ability to produce the lactase enzyme into adulthood, a condition often referred to as lactase non-persistence. Individuals with this genotype may experience symptoms such as bloating, gas, or diarrhea after consuming lactose-containing dairy products. Some research also suggests this genotype may be linked to different lipid profiles compared to those with persistence genotypes.
This is the most common genotype globally, though its frequency is significantly lower in populations of Northern European descent.
Lactase persistence
This genotype is associated with the continued production of the lactase enzyme into adulthood, allowing for the digestion of lactose. Individuals with this genotype are generally able to consume dairy products without the digestive distress associated with lactose intolerance. This genotype is considered a dominant trait for lactase persistence.
This genotype is highly prevalent in populations of Northern European ancestry, where it is a common adaptation.
Lactase persistence
This genotype is associated with the continued production of the lactase enzyme into adulthood, facilitating the digestion of lactose. Individuals with this genotype typically tolerate dairy products well and do not experience the symptoms of lactose intolerance. Research indicates this genotype is strongly correlated with the lactase persistence trait.
This genotype is common in Northern European populations, reflecting the evolutionary adaptation for dairy consumption in these groups.
What is the rs4988235 Variant?
The rs4988235 variant is a single nucleotide polymorphism (SNP) located approximately 14,000 base pairs upstream of the LCT gene, specifically within an intron of the neighboring MCM6 gene. This region acts as a transcriptional enhancer for the LCT gene. In many human populations, the production of the enzyme lactase—which is required to break down lactose, the primary sugar in milk—naturally declines after childhood. The rs4988235 variant is one of several known genetic markers that can influence whether this enzyme production continues into adulthood. Because it sits in a regulatory region, the specific allele present at this location can affect how much lactase is expressed in the small intestine, thereby influencing how an individual processes dietary lactose.
The Role of the LCT Gene
The LCT gene provides instructions for making the enzyme lactase, also known as lactase-phlorizin hydrolase. This enzyme is essential for the digestion of lactose, a sugar found in milk and other dairy products. In most mammals, lactase activity is high during infancy to support nursing but decreases significantly after weaning. In humans, however, the trait of lactase persistence allows some adults to continue producing sufficient levels of lactase to digest lactose without experiencing digestive discomfort. This trait is considered a classic example of recent human evolution, likely driven by historical dietary shifts toward the consumption of animal milk. The rs4988235 variant serves as a primary genetic proxy for this trait in many populations, particularly those of European descent, where the persistence allele is highly prevalent.
Research and Evidence
The association between rs4988235 and lactase persistence is supported by strong scientific evidence. Research consistently shows that the T allele is linked to higher levels of lactase expression in the intestinal mucosa, enabling the digestion of lactose in adulthood. Conversely, the C allele is associated with lower lactase expression and a higher likelihood of lactose non-persistence. While this variant is a robust marker in European populations, it is important to note that the genetic architecture of lactase persistence is complex and varies globally. Other variants, such as rs41525747 and rs41380347, also contribute to this trait in different populations. Furthermore, while rs4988235 is a reliable indicator for lactose digestion, it does not account for all cases of lactose intolerance, which can also be influenced by environmental factors, gut microbiome composition, and other underlying health conditions.
Interpreting Your Information
Understanding your genotype at rs4988235 can provide insight into your genetic predisposition for lactase persistence, but it should not be used as a medical diagnosis. If you experience symptoms such as bloating, gas, or diarrhea after consuming dairy, these may be signs of lactose intolerance, regardless of your genetic profile. Genetic testing for this variant is not a substitute for clinical evaluation by a healthcare professional. If you have concerns about your digestive health or nutritional needs, it is best to discuss them with a doctor or a registered dietitian. They can help determine if your symptoms are related to lactose intolerance or another condition and provide appropriate guidance on dietary adjustments. Never use genetic information to make significant changes to your diet or health management without professional medical advice.
How common is this variant?
The lactase persistence allele is highly common in Northern European populations, reaching frequencies of approximately 80%, while it is significantly less common in many other global populations.
Frequently asked questions
Does having the CC genotype mean I am lactose intolerant?
The CC genotype is associated with a genetic predisposition to lactase non-persistence, which often leads to lactose intolerance. However, it is not a definitive diagnosis, as individual tolerance levels can vary significantly.
Can I change my genotype for rs4988235?
No, your genotype is determined at conception and cannot be changed. It is a permanent part of your genetic makeup.
Is this the only gene that affects lactose digestion?
While rs4988235 is a major marker, other genetic variants and environmental factors also play a role in how your body processes lactose. Lactose intolerance can also be caused by secondary factors like intestinal injury or illness.
Should I avoid dairy if I have the CC genotype?
Not necessarily. Many people with the CC genotype can still tolerate small amounts of lactose or may choose to consume lactose-free dairy products. You should consult with a healthcare provider to determine the best dietary approach for your specific needs.
Sources & further reading
Educational information only, last refreshed 10/5/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Rare variant in the lactase persistence locus marking archaic Eurasian and pastoralist ancestral haplotype variation.
Functional enhancer polymorphism situated upstream of the lactase promoter associated with adult-type lactase persistence in pastoralist populations of Sub-Saharan Africa.
This variant is the primary genetic marker for lactase persistence, determining the ability to digest lactose into adulthood.
This variant is located in the regulatory region of the lactase gene and is strongly associated with lactase persistence (the ability to digest lactose into adulthood).