LDLR rs121918404: Understanding Familial Hypercholesterolemia Risks
The rs121918404 variant is a specific genetic change located within the LDLR gene. It is associated with autosomal dominant familial hypercholesterolemia, a condition characterized by the body's reduced ability to clear low-density lipoprotein (LDL) cholesterol from the blood.
What each genotype means
Typical receptor function
This genotype represents the common, non-variant form of the LDLR gene at this position. It is not associated with the familial hypercholesterolemia linked to this specific genetic variant.
This is the most common genotype found in the general population across all ancestries.
Increased cholesterol risk
This genotype indicates the presence of one copy of the variant, which is associated with autosomal dominant familial hypercholesterolemia. This condition can impair the function of the low-density lipoprotein receptor, potentially leading to elevated LDL cholesterol levels and increased cardiovascular risk. Please discuss these results and any necessary lipid management with your clinician.
This genotype is rare in the general population.
High cholesterol risk
This genotype indicates the presence of two copies of the variant, which is associated with a more severe form of familial hypercholesterolemia. This can significantly impair the function of the low-density lipoprotein receptor, often resulting in markedly elevated LDL cholesterol and a higher risk for premature cardiovascular disease. Please consult with a specialist or your primary care provider to discuss appropriate clinical management.
This genotype is extremely rare in the general population.
What is the rs121918404 Variant?
The rs121918404 variant is a single nucleotide polymorphism (SNP) found within the LDLR gene, which is located on chromosome 19. In genetics, a SNP represents a variation at a single position in the DNA sequence. This specific variant is categorized as a trait-associated marker. Because it occurs within the LDLR gene, it can potentially alter the instructions the body uses to build the low-density lipoprotein receptor protein. When a variant occurs in a critical region of a gene, it may lead to a loss of function or a reduction in the efficiency of the resulting protein. Researchers track these variants to understand how they contribute to metabolic differences between individuals. While many variants in the human genome are neutral, those located in genes responsible for essential physiological processes, such as cholesterol metabolism, are often studied for their potential to influence health outcomes.
The Role of the LDLR Gene
The LDLR gene provides the essential blueprint for creating the low-density lipoprotein receptor. This protein acts like a molecular gatekeeper on the surface of cells, particularly in the liver. Its primary job is to bind to LDL particles—often referred to as 'bad' cholesterol—circulating in the bloodstream and pull them into the cell to be broken down. By removing these particles from the blood, the LDLR protein helps maintain healthy cholesterol levels. When the LDLR gene contains a pathogenic variant, the resulting receptors may be produced in insufficient numbers, or they may fail to bind to LDL particles effectively. This disruption causes LDL cholesterol to accumulate in the blood, which is a hallmark of familial hypercholesterolemia. Understanding this gene is vital because it highlights how a single genetic instruction can have a profound impact on how the body processes fats and maintains cardiovascular health.
Research and Clinical Associations
Scientific research associates the rs121918404 variant with autosomal dominant familial hypercholesterolemia. The evidence strength for this association is currently considered moderate. In clinical genetics, 'autosomal dominant' means that inheriting a single copy of the variant from one parent is sufficient to potentially manifest the associated trait. Studies on familial hypercholesterolemia consistently show that variants in the LDLR gene are the most common cause of this condition, accounting for a significant majority of diagnosed cases. However, it is important to note that the clinical expression of such variants can vary between individuals due to other genetic and environmental factors. Researchers use databases like ClinVar and the GWAS Catalog to aggregate findings from clinical testing and population studies. Because this variant is rare, ongoing research is necessary to fully characterize its penetrance—the proportion of people with the variant who actually develop the clinical symptoms of high cholesterol.
Population Frequency and Distribution
The rs121918404 variant is classified as rare across global populations. In genetic studies, 'rare' typically indicates that the variant is found in a very small percentage of the general population. Because it is not a common polymorphism, it is not frequently observed in large-scale genomic databases that track common human variation. This rarity is consistent with many variants that cause hereditary metabolic conditions, as these are often subject to selective pressure. The distribution of such variants can also be influenced by ancestry, with some mutations appearing more frequently in specific geographic or ethnic groups due to founder effects. Because the variant is rare, individuals are unlikely to encounter it in standard, broad-spectrum genetic screening tests unless those tests are specifically designed to look for rare, pathogenic mutations associated with familial hypercholesterolemia.
Interpreting Your Genetic Information
If you have received information about the rs121918404 variant, it is important to understand what this means in a practical sense. Genetic variants are not diagnoses; they are pieces of information that describe your biological predisposition. A variant in the LDLR gene does not guarantee that an individual will develop severe health issues, but it does suggest a need for clinical monitoring. You cannot 'fix' a genetic variant, but you can manage the associated health risks through lifestyle choices and, if necessary, medical interventions prescribed by a healthcare professional. If you are concerned about your cholesterol levels or your family history, the most effective step is to consult with a doctor or a genetic counselor. They can interpret your results in the context of your overall health, family history, and blood lipid panels. Never make changes to your medication or health regimen based solely on a genetic report without professional guidance.
How common is this variant?
The rs121918404 variant is considered rare in the general population, meaning it is not commonly found in standard genomic datasets.
Frequently asked questions
What is familial hypercholesterolemia?
Familial hypercholesterolemia is an inherited condition that causes very high levels of LDL cholesterol in the blood. It is primarily caused by mutations in genes like LDLR that prevent the body from effectively clearing cholesterol.
Does having this variant mean I have high cholesterol?
Not necessarily. While this variant is associated with a higher risk of familial hypercholesterolemia, genetic predisposition is only one factor. You should have your blood cholesterol levels checked by a doctor to understand your actual health status.
Can I change my LDLR gene?
No, you cannot change your genetic sequence. However, you can manage the health effects of a genetic variant through diet, exercise, and medications as recommended by your healthcare provider.
Should I be worried if I have this variant?
Finding a rare variant can be concerning, but it is important to discuss the results with a medical professional. They can provide context based on your personal health history and determine if any clinical follow-up is necessary.
Sources & further reading
Educational information only, last refreshed 10/2/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic missense variant altering low-density lipoprotein receptor function and predisposing to severe familial hypercholesterolemia.
This pathogenic variant in the LDLR gene is a contributor to familial hypercholesterolemia, leading to significantly elevated LDL cholesterol levels.
Variant in the LDLR 3' UTR region associated with statin efficacy, often studied in East Asian cohorts.
A variant in the 3' UTR of the LDLR gene associated with variations in statin therapeutic response.
Synonymous variant in the LDLR gene associated with plasma LDL cholesterol levels.
This variant is a well-established marker associated with LDL cholesterol levels and risk of coronary artery disease.