APOE and Alzheimer disease: Most of the AD cases have a late onset (94%, approximately), and by far, only the ε4-allele polymorphism of the apolipoprotein E (APOE4) has been consistently associated with an increment in the risk for developing the sporadic form of AD; yet recently some other chromosomal loci associated with the disease (chromosomes 1, 7 and 8) have been described [12].