||Two copies of ApoE3 Christchurch variant (apparently)
||Carrier of one ApoE3 Christchurch variant (most likely)
||common in clinvar
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.
There is evidence to suggest that ApoE-ε3ch may be associated with strong resistance to developing Alzheimer's disease. A 2019 study  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 (, 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 , heterozygous ApoE-ε3ch carriage may also be convey protection against sporadic Alzheimer's disease.