PDCD4 and Hypercholesterolemia: Although not sufficient to cause the disease by itself, inheritance of apolipoprotein E epsilon 4 (ApoE4; 19q13.2) allele constitutes a major genetic risk factor for developing EOAD as well as LOAD predisposition and hypercholesterolaemia [59, 60] and could act in synergy with other susceptible genes, for example, programmed cell death protein 4 (PDCD4) and evolutionarily conserved signaling intermediate in Toll pathway (ECSIT), in a complex interaction with environmental factors [61–65] (Table 1).