PCSK9 and early-onset autosomal dominant Alzheimer disease: Additionally, a Mendelian randomization study of 111,194 Danish individuals showed that lower LDL cholesterol levels due to PCSK9 LOF variants rs11591147, rs148195424, and rs562556 did not increase the risk of Alzheimer’s disease, and instead may have a causal effect in reducing the risk of AD (Benn et al., 2017).