 Also, research has been put on concerning apolipoprotein E genotypes; this polymorphism has three alleles (*e2, *e3, and *e4)and was determined from research because of its known association with increased cholesterol levels and risk of coronary heart disease in Japanese Americans.Specifically too, the apolipoprotein *e4 allele is linked to Alzheimer's disease as well.Also, there is increased coronary heart disease in Japanese-American men with a mutation in the cholesterol ester transfer protein gene despite having increased levels of HDL.