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Observing a causal effect on ALS without the need for a trad
For anyone studying research against neurodegenerative diseases, it is striking to note the large number of studies which each claim to have identified a key element different from the others, and which would be a causative factor of the disease. In addition, many studies are contradictory.
In epidemiology, Mendelian randomization is a method of using measured gene variation, known to express the causal effect of exposure to a disease in observational studies, without the need for a traditional randomized clinical trial. Better still, it allows us to escape traditional biases in epidemiological studies, such as reverse causation and confusion.
Among the various genetic and environmental factors that have been identified as being associated with ALS, the association between blood lipid metabolites and ALS has recently received considerable attention. The associations between lipids and ALS are strong and comparable in strength to many risk factors for ALS previously identified.
Scientists have studied the causal effects of four blood lipid traits on the risk of ALS:
* high density lipoprotein,
* low density lipoprotein (LDL),
* total cholesterol,
* and triglycerides.Taking advantage of the instrument variables from several large-scale association studies on the genome in European and Asian populations, the authors performed one of the most important and comprehensive Mendelian randomization analyzes to date on the causal relationship between lipids and ALS. Among the four lipids, they found that * only LDL is causally associated with ALS * and that a higher level of LDL increases the risk of ALS in European and East Asian populations.
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