LDLR rs121908486: Genetics, Cholesterol, and FH Risk
The genetic variant rs121908486 is a rare missense mutation located within the low-density lipoprotein receptor (LDLR) gene. It alters the amino acid sequence of the receptor, disrupting cellular uptake of low-density lipoprotein cholesterol from circulation. This variant is clinically associated with familial hypercholesterolemia, an inherited condition marked by markedly elevated LDL cholesterol and an increased risk of early cardiovascular events.
What each genotype means
Typical LDL receptor function
You carry two reference copies of this region in the LDLR gene. This genotype is not associated with LDLR-related familial hypercholesterolemia, indicating baseline genetic risk for this specific marker. Cardiovascular risk remains influenced by lifestyle and other common genetic variants.
Carried by more than 99.9% of individuals across all major global populations.
Elevated familial hypercholesterolemia risk
You carry one copy of the pathogenic missense variant in the LDLR gene. In clinical studies, this variant is associated with significantly impaired clearance of low-density lipoprotein cholesterol from circulation, consistent with heterozygous familial hypercholesterolemia. Because this condition substantially elevates early cardiovascular risk, consulting a medical professional for lipid monitoring and management is recommended.
Extremely rare in the general population, observed in fewer than 1 in 10,000 individuals in large reference datasets like gnomAD.
Severe hypercholesterolemia risk
You carry two copies of this pathogenic variant in the LDLR gene. Inheriting two non-functional LDLR alleles is associated with homozygous familial hypercholesterolemia, a rare condition characterized by extremely high LDL cholesterol from birth and rapid progression of cardiovascular disease. Comprehensive clinical evaluation and specialized lipid management are strongly indicated.
Exceedingly rare globally, with an estimated prevalence of less than 1 in several million people.
Understanding the rs121908486 Variant and Location
The single nucleotide polymorphism rs121908486 sits on chromosome 19 inside the coding sequence of the LDLR gene. At this position, a nucleotide substitution alters the genetic code for the LDLR protein, resulting in an amino acid change that impairs normal receptor architecture. Rather than representing a common benign polymorphism that subtly influences traits across a general population, rs121908486 is classified in major clinical databases like ClinVar as a rare pathogenic or likely pathogenic missense variant. Variants in this locus affect key structural regions of the low-density lipoprotein receptor, which are essential for correct protein folding, transport through the cell to the surface membrane, or ligand binding. Because this variant directly changes an amino acid in a functional domain, it can significantly diminish the receptor's capacity to process circulating lipid particles.
The Biological Role of the LDLR Gene
The LDLR gene provides the cellular instructions for constructing the low-density lipoprotein receptor. Expressed abundantly on hepatocytes in the liver, these cell-surface transmembrane receptors bind circulating low-density lipoprotein (LDL) particles by recognizing apolipoprotein B. Once bound, the receptor-lipoprotein complex undergoes endocytosis, clearing LDL particles out of the bloodstream and into the cell where cholesterol is repurposed or broken down. The receptor then typically recycles back to the cellular surface to clear additional particles. When a functional missense mutation occurs in the LDLR gene, the resulting receptors may be unstable, fail to reach the cell membrane, or lose their ability to bind LDL particles efficiently. Consequently, low-density lipoproteins remain trapped in the bloodstream, leading to progressive accumulation of plasma cholesterol.
Clinical Evidence and Association with Hypercholesterolemia
Familial hypercholesterolemia (FH) is predominantly an autosomal dominant genetic disorder caused by mutations in the LDLR gene. Scientific literature documented in resources such as ClinVar, GenCC, and PubMed associates pathogenic variants at rs121908486 with elevated circulating LDL cholesterol levels. In heterozygous individuals, having one altered allele significantly reduces normal receptor capacity, frequently resulting in lifelong LDL cholesterol levels greater than 190 mg/dL in adults. If unmanaged, this prolonged vascular exposure to high cholesterol substantially increases the risk of premature coronary artery disease. However, specific functional research on rs121908486 remains classified as having limited evidence relative to more frequently studied founder mutations, meaning its exact cellular impact and penetrance continue to be curated by expert panels.
Population Frequency and Demographics
According to large-scale population sequencing repositories such as the Genome Aggregation Database (gnomAD), the rs121908486 variant is exceptionally rare across the general human population. Its overall allele frequency is estimated at less than 0.0001 (below 0.01%), with zero to very few carriers observed in unselected population cohorts across diverse continental ancestries. Because familial hypercholesterolemia affects approximately 1 in 250 to 1 in 300 individuals globally, pathogenic variants are distributed across hundreds of distinct familial mutations rather than a single widespread allele. The rs121908486 variant usually surfaces only in clinical sequencing panels evaluating individuals or families with severely elevated cholesterol levels, tendon xanthomas, or early personal or family histories of atherosclerotic cardiovascular disease.
Navigating Results: What This Information Means for You
Finding this variant in raw consumer data requires caution, as consumer direct-to-consumer arrays often yield false-positive results when calling very rare alleles. Genetic information does not serve as a clinical diagnosis on its own. Individuals who identify an atypical result at rs121908486 or have personal concerns regarding lipid profiles should consult a medical provider or genetic counselor for clinical-grade diagnostic confirmation. A standard lipid panel remains the primary diagnostic and monitoring tool for cholesterol management. Lifestyle factors, dietary habits, and medications—such as statins, ezetimibe, or PCSK9 inhibitors—are evaluated clinically to manage cardiovascular risk. Patients taking or considering lipid-lowering therapies should always discuss dosing and prescriptions directly with their clinician or pharmacist.
How common is this variant?
The rs121908486 variant is exceedingly rare in the general population, with an allele frequency estimated at less than 0.0001 in gnomAD across all ancestries.
Frequently asked questions
Does having the rs121908486 variant guarantee I have high cholesterol?
While pathogenic LDLR variants are strongly linked to familial hypercholesterolemia, genetics represents risk rather than certainty. Penetrance, modifier genes, and overall lifestyle can influence exact cholesterol levels, making a clinical blood lipid profile the gold standard for assessment.
Can consumer DNA tests reliably identify rare variants like rs121908486?
Direct-to-consumer genotyping arrays are prone to false positives when detecting very rare single-nucleotide variants. Any unexpected result from an informal test should be verified via a clinical-grade diagnostic assay ordered by a physician.
How is familial hypercholesterolemia passed down to children?
LDLR-related familial hypercholesterolemia typically follows an autosomal dominant inheritance pattern. This means that a person with one copy of the pathogenic variant has a 50% chance of passing that variant on to each biological child.
What medical steps are taken if someone carries this variant?
Healthcare providers generally monitor fasting lipid panels, evaluate family history, and assess cardiovascular health. When treatment is needed, clinicians determine an appropriate regimen involving lifestyle adjustments and lipid-lowering medications, which patients should always review with their doctor or pharmacist.
Sources & further reading
Educational information only, last refreshed 9/13/2026. 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.