Apolipoprotein E (ApoE) genes: rs429358 and rs7412

The apolipoprotein E (ApoE) gene makes a protein which, when combined with fat, becomes a lipoprotein.

The lipoprotein ApoE is a very low-density lipoprotein, responsible in part for removing cholesterol from the bloodstream. Variations in ApoE affect cholesterol metabolism, which in turn alter your chances of having heart disease and in particular a heart attack or a stroke. Variations in ApoE are also associated with altered odds of having Alzheimer's disease and other diseases.

There are 3 allelic variants of ApoE, as defined by two SNPs, rs429358 and rs7412 known as:

- ApoE-ε2
- ApoE-ε3
- ApoE-ε4

The proteins produced by these genes are called ApoE2, ApoE3, and ApoE4.

The most common variant overall is the "standard" ApoE-ε3, and therefore more people inherited one ApoE-ε3 from each parent than any other of the possible pairs of variants. 

Apo-ε2/ε2 - rs429358 and rs7412 (T;T) (T;T) - has the lowest risk. 

Apo-ε3/ε3 - rs429358 and rs7412 (T;T) (C;C) - is the the most common.

Apo-ε4/ε4  - rs429358 and rs7412 (C;C) (C;C) - has 11 times higher increased Alzheimer's risk. 

References:

https://www.snpedia.com/index.php/APOE