rs121918393
A SNP in the APOE gene on chromosome 19. Its most notable genotype is A;A: Two copies of ApoE3 Christchurch variant (apparently)
- Gene
- APOE
- Location
- Chr 1944,908,756 (GRCh38)
- Highest magnitude
- 6.0Very important
- Tested on
- Not on consumer chips
Genotypes
As shown in 23andMe and AncestryDNA files.
- A;AMost notableNot ratedTwo copies of ApoE3 Christchurch variant (apparently)
- A;CNot ratedCarrier of one ApoE3 Christchurch variant (most likely)
- C;CGoodcommon in clinvar
On SNPedia: (A;A), (A;C), (C;C). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.
Related
Conditions, medicines and genes
Other APOE SNPs
- rs121918394A;GHyperlipoproteinemia, type IIIVery important
- rs267606664A;GRare ApoE1 allele; clinical significance unclearVery important
- i5000217C;Tfamilial hyperlipoproteinemia, type IIIImportant
- rs387906567C;TFamilial type 3 hyperlipoproteinemiaImportant
- rs199768005A;TMarked reduced risk of Alzheimer's DiseaseWorth knowing
- rs449647T;Tlower levels of ApoEWorth knowing
- rs429358C;Cone of 2 snps relevant to classifying APOE genotypeMinor
- rs7412C;Cpart of APOE4 genoset evaluationMinor
Notes
From SNPedia
Show notes, about 270 words
aka c.460C>A (p.Arg154Ser or R154S); but also known based on older literature as p.Arg136Ser or R136S This SNP is a variant form of an ApoE-ε3 allele, called the Christchurch mutation or ApoE-ε3ch. The variant has been strongly associated with type III hyperlipoproteinemia.jlr.org There is evidence to suggest that ApoE-ε3ch may be associated with strong resistance to developing Alzheimer's disease. A 2019 study nature.com reported that that a carrier of a pathogenic PSEN1 mutation, known to cause early-onset Alzheimer's disease, who was also a homozygous ApoE3ch carrier, did not show cognitive symptoms before her seventies, almost three decades after expected onset. Autosomal dominant forms of Alzheimer's disease and sporadic Alzheimer's disease show largely similar pathogenesis. Likewise, common APOE alleles(ApoE-ε2, ApoE-ε3, and ApoE-ε4) have similar effects in autosomal dominant Alzheimer's disease (doi.org, ApoE-ε4 carriers have earlier onset, ApoE-ε2 alleles have later onset). Together, this these findings suggest that being a homozygous ApoE-ε3ch carrier will potentially also convey protection against sporadic Alzheimer's disease. Furthermore, assuming that ApoE-ε3ch follows an allele-dose risk pattern similar to what has been observed for common APOE alleles doi.org, heterozygous ApoE-ε3ch carriage may also be convey protection against sporadic Alzheimer's disease.
A;A
see text via main rs-page
A;C
see text via main rs-page
Source and license
Adapted from rs121918393 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.
SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.