Causal effects of serum lipid biomarkers on early age-related macular degeneration using Mendelian randomization

Age-related macular degeneration (AMD) is one of the major causes of vision loss. Early AMD needs to be taken seriously, but the causal effects of lipid biomarkers on early AMD remain unclear.

In this study, two-sample Mendelian randomization (MR) analysis was performed to systematically assess the causal relationships between seven serum lipid biomarkers (apolipoprotein A (ApoA), apolipoprotein B (ApoB), total cholesterol (CHOL), high-density lipoprotein cholesterol (HDL-C), direct low-density lipoprotein cholesterol (LDL-C), lipoprotein A [Lp(a)], and triglycerides (TG)) and risk of early AMD. In total, 14,034 cases and 91,214 controls of European ancestry were included in the analysis (number of SNPs = 11,304,110).

MR estimates revealed that a higher HDL-C level is strongly associated with increased risk of early AMD (OR = 1.25, 95% CI: 1.15-1.35, P = 2.61 × 10^-8). In addition, level of ApoA is also positively associated with risk of early AMD (OR = 2.04, 95% CI: 1.50-2.77, P = 6.27 × 10^-6). Conversely, higher levels of TG significantly decrease the risk of early AMD (OR = 0.77, 95% CI: 0.71-0.84, P = 5.02 × 10^-10). Sensitivity analyses further supported these associations. Moreover, multivariable MR analyses, adjusted for the effects of correlated lipid biomarkers, yielded similar results.

This study identifies causal relationships between elevated circulating HDL-C/ApoA levels and increased risk of early AMD, in addition to finding that TG specifically reduces the risk of early AMD. These findings contribute to a better understanding of the role of lipid metabolism in drusen formation, particularly in early AMD development.