Does variation at SORT1 (rs12740374) affect LDL-C and apolipoprotein B levels?

The genetic locus at chromosome 1p13.3, specifically the noncoding regulatory variant rs12740374, plays a pivotal role in cardiovascular health by modulating the expression of SORT1, which encodes the hepatic sorting receptor sortilin.

Mechanistic pathways

• Transcription factor binding: The rs12740374 variant functions as a liver-specific expression quantitative trait locus (eQTL). In hepatocytes, the allele associated with altered lipid profiles creates a binding site for the CCAAT/enhancer-binding protein (C/EBP) transcription factor, directly modulating SORT1 expression.
• Intracellular trafficking and degradation: Hepatic sortilin acts as a cargo-sorting receptor within the trans-Golgi network and endosomal system. It binds newly synthesized apolipoprotein B-100 (apoB100)—the structural backbone of VLDL and LDL—and diverts these nascent lipoproteins toward lysosomal degradation, preventing their over-secretion.
• Lipoprotein clearance: Beyond restricting VLDL output, sortilin expressed on the hepatocyte cell surface acts as an endocytic receptor, binding circulating LDL particles to facilitate their cellular uptake and clearance.

Clinical implications

• Lipid profile modulation: Large-scale genome-wide association studies (GWAS) and fine-mapping confirm that this regulatory variation drives concordant changes in both circulating LDL cholesterol (LDL-C) and apolipoprotein B (apoB) particle numbers.
• Cardiovascular risk: Clinical cohort data show that the protective allele reduces circulating apoB levels by approximately 11% and LDL-C by about 6 mg/dL. Over a lifetime, this genetically driven reduction translates into a significantly lower risk of myocardial infarction.

Bottom line

• Genetic variation at the SORT1 locus (specifically rs12740374) regulates circulating LDL-C and apoB levels through a hepatic eQTL mechanism. Increased sortilin expression reduces atherogenic lipoprotein levels via a dual mechanism of presecretory lysosomal degradation and enhanced hepatocyte clearance.