Shared genetic link and causal inference between blood lipids, lipid-lowering drugs and amyotrophic lateral sclerosis

Growing evidence suggests that abnormal lipid metabolism occurs in amyotrophic lateral sclerosis, even in the presymptomatic stage, implying an etiologic link. However, the genetic mechanism underlying altered lipid levels in amyotrophic lateral sclerosis remains elusive. Therefore, in this study, we performed genetic correlation analysis, a cross-trait meta-analysis, tissue-specific enrichment analysis, and bidirectional two-sample Mendelian randomization analysis of European population to explore whether there is a genetic and causal relationship between lipids and amyotrophic lateral sclerosis. The effect of lipid-lowering drugs on amyotrophic lateral sclerosis was also evaluated using a drug target Mendelian randomization approach. The results showed a positive genetic correlation between amyotrophic lateral sclerosis and both high-density lipoprotein cholesterol and apolipoprotein A1 and identified 71 independent shared loci between amyotrophic lateral sclerosis and high-density lipoprotein cholesterol, as well as 55 independent shared loci between amyotrophic lateral sclerosis and apolipoprotein A1. These shared loci were enriched in the lipid metabolic pathway and the alcohol metabolic pathway. Further Mendelian randomization analysis targeting lipid-lowering drugs showed that single nucleotide polymorphisms within the ACLY and PCSK9 genes had a protective effect against amyotrophic lateral sclerosis risk by decreasing low-density lipoprotein cholesterol. The combination of ACLY and PCSK9 inhibitors has a greater protective effect on amyotrophic lateral sclerosis risk than that of PCSK9 inhibitors alone. In summary, there is a common genetic structure between lipids and amyotrophic lateral sclerosis. Mendelian randomization analysis supports an association between elevated blood lipids and the risk of developing amyotrophic lateral sclerosis, and the use of ACLY or PCSK9 inhibitors may improve disease prognosis.