Does the LDLR rs6511720 T allele lower LDL cholesterol and does GG indicate absence of that allele?

Research into the genetic determinants of lipid profiles has consistently identified the LDLR gene—which encodes the low-density lipoprotein receptor—as a critical regulator of blood cholesterol. The rs6511720 variant within this gene is a well-established genetic marker used to understand individual variability in LDL cholesterol (LDL-C) levels and cardiovascular risk.

Clinical and effectiveness evidence

Large-scale genomic analyses, including data from the Global Lipids Genetics Consortium (GLGC) and the CARDIoGRAM study, confirm a robust association between the rs6511720 T allele and lower LDL cholesterol.

• Effect Size: Carrying the T allele is associated with a reduction in LDL-C of approximately 6.99 mg/dL, or roughly 0.22 mmol/L per allele (p = 3.85 × 10⁻²⁶²).
• Cardiovascular Impact: This reduction in LDL-C translates to a significant clinical benefit, with T-allele carriers showing a roughly 12% reduced risk of coronary heart disease compared to non-carriers.
• Genotype Frequency: The GG genotype is the most common (ancestral) state in the general population, representing approximately 85-90% of individuals in European cohorts. Because it lacks the T variant, individuals with the GG genotype do not experience this genetically driven reduction in LDL-C and typically exhibit higher baseline cholesterol levels than those with GT or TT genotypes.

Mechanistic explanations

The influence of this variant on cholesterol levels is driven by specific regulatory changes in the liver:

• Enhanced Transcription: The T allele at rs6511720 (located in intron 1) creates a novel transcription factor binding site. Functional assays in Huh7 hepatoma cells demonstrate that this allele increases LDLR promoter activity by 24% to 29%.
• Receptor Expression: This increased promoter activity leads to higher expression of LDL receptors on the surface of liver cells.
• LDL Clearance: With a higher density of receptors, the liver can more efficiently capture and clear LDL particles from the bloodstream, directly resulting in lower circulating LDL-C levels. The GG genotype lacks this enhanced binding capacity, resulting in standard receptor expression.

Bottom line

The claim is strongly supported by high-quality genomic and functional evidence. The T allele of rs6511720 is a potent LDL-lowering variant that increases receptor expression; consequently, the GG genotype indicates the absence of this protective allele and is associated with higher average LDL cholesterol levels.