Overview
APOB encodes apolipoprotein B, the main protein of LDL particles (Low-Density Lipoprotein). It is crucial for transporting cholesterol to cells but is considered a primary cause of vascular calcification at high levels.
2p24.1 (Chromosome 2)
Metabolism
Complex
T allele ~25-35%
Function & Significance
APOB is the ‘identity card’ of LDL particles:
- Lipid Transport: It enables particles to move through the blood and distribute cholesterol.
- Receptor Binding: Cells recognize APOB and take up the LDL particle to utilize the cholesterol.
- Atherogenicity: If too many APOB particles are in the blood (especially ‘small dense LDL’), they can penetrate vessel walls, triggering inflammation and plaque formation (atherosclerosis).
⚠️ Why APOB is more informative than LDL
An LDL laboratory value only measures the *amount* of cholesterol. APOB measures the *number* of dangerous particles. Since each LDL particle carries exactly one APOB molecule, the APOB value is often a more precise indicator of true cardiovascular risk.
🧬 Relevant SNPs
The XbaI polymorphism (rs693):
2:21044037
/
Significance: rs693 (C>T) – A variant associated with the efficiency of LDL clearance from the blood.
• CC (Wild type): Normal APOB and LDL values.
• TT / CT: T-allele carriers statistically tend to have higher APOB and LDL cholesterol levels.
🛑 Cardiovascular Risk
Studies have shown that carriers of the T allele may have a moderately increased risk of coronary heart disease if blood lipid levels are not kept under control through diet or medication.
📚 Data Sources
- OMIM: #107730 – Online Mendelian Inheritance in Man
- dbSNP: rs693 – SNP Database (NCBI)
- Arteriosclerosis, Thrombosis, and Vascular Biology: APOB and Atherosclerosis
- European Heart Journal: Lipid management guidelines
Last Update: February 2026
Biological Function
Associated Conditions
Analyzed Markers
XbaI Polymorphism - T-allele: Associated with higher APOB levels, higher LDL values, and increased risk for cardiovascular diseases.