Lipoprotein (a): a Unique Independent Risk Factor for Coronary Artery Disease

Area of Science:

• Cardiovascular Science
• Genetics
• Biochemistry

Background:

• Coronary artery disease (CAD) is a leading cause of mortality and morbidity globally, with a notably higher prevalence in the Indian population.
• Genetic susceptibility is suspected to contribute to the increased CAD rates in Indians.
• Lipoprotein(a) [Lp(a)], an independent genetic risk marker for atherosclerosis and cardiovascular disease, is of significant importance in this context.

Purpose of the Study:

• To highlight the importance of Lipoprotein(a) [Lp(a)] as a genetic risk marker for atherosclerosis in the Indian population.
• To discuss the genetic basis of Lp(a), including the role of the LPA gene and apolipoprotein (a) [apo(a)] isoforms.
• To address the lack of defined upper limits for Lp(a) levels in Indians and the challenges in its measurement.

Main Methods:

• Review of existing literature on Lp(a), apo(a) polymorphism, and CAD in the Indian population.
• Discussion of the structural homology of Lp(a) with LDL and plasmin and its proposed pathogenic mechanisms.
• Analysis of the challenges in standardizing Lp(a) assays due to apo(a) size heterogeneity.

Main Results:

• Lp(a) is an atherogenic lipoprotein composed of LDL and apo(a), with apo(a) exhibiting significant polymorphism.
• An inverse relationship exists between Lp(a) concentration and apo(a) isoform size, indicating functional diversity.
• Proposed pathogenic mechanisms involve Lp(a)'s structural similarity to LDL and plasmin, linking atherosclerosis and thrombosis.

Conclusions:

• The genetic heterogeneity of apo(a) and its impact on Lp(a) levels are crucial for understanding CAD risk in Indians.
• Standardized Lp(a) measurement and defined population-specific cut-off levels are needed for the Indian population.
• While no specific therapies target Lp(a) currently, research into apo(a) synthesis modifiers is ongoing.