{{Rsnum
|rsid=28371733
|Chromosome=22
|Orientation=minus
|geno1=(A;A)
|geno2=(A;G)
|geno3=(G;G)
|Gene=CYP2D6
|position=42522916
|Assembly=GRCh37
|GenomeBuild=37.1
|dbSNPBuild=131
}}The wild type allele for this SNP is (G) in minus orientation. When it changes to (C) it is known as 3877G>C and is a marker for non-functioning variant CYP2D6*4H. 

When it changes to (A) it is known as 3877G>A and is a marker for variant CYP2D6*52 which is possibly a decreased functioning variant, though more study is needed.{{PMID|19364831}}

Please note that this is in minus orientation and the 3877G>C version is subject to [[ambiguous flip]].

{{on chip | 23andMe v1}}
{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}