{{Rsnum
|rsid=28399424
|Gene=CYP1A2
|Chromosome=15
|position=74754828
|Orientation=plus
|ReferenceAllele=C
|MissenseAllele=T
|GMAF=0.001837
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Gene_s=CYP1A2
}}{{ population diversity
| geno1=(C;C)
| geno2=(C;T)
| geno3=(T;T)
| CEU | 0.0 | 0.0 | 0.0
| HCB | 0.0 | 0.0 | 0.0
| JPT | 0.0 | 0.0 | 0.0
| YRI | 0.0 | 0.0 | 0.0
| ASW | 0.0 | 0.0 | 0.0
| CHB | 0.0 | 0.0 | 0.0
| CHD | 0.0 | 0.0 | 0.0
| GIH | 0.0 | 0.0 | 0.0
| LWK | 99.1 | 0.9 | 0.0
| MEX | 98.3 | 1.7 | 0.0
| MKK | 0.0 | 0.0 | 0.0
| TSI | 0.0 | 0.0 | 0.0
| HapMapRevision=28
}}[[rs28399424]], also known as 5090C>T or R431W, is a SNP in the [[CYP1A2]] gene.

The [[rs28399424]](T) allele defines the CYP1A2*6 decreased activity variant.

{{PharmGKB
|RSID=rs28399424
|Name_s=CYP1A2:5090C>T; CYP1A2*6
|Gene_s=CYP1A2
|Feature=Exon
|Evidence=PubMed ID:14725854
|Annotation=Reduced expression.
|Drugs=
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA161145047
}}

{{on chip | 23andMe v1}}
{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}
{{on chip | FTDNA2}}
{{on chip | HumanOmni1Quad}}
{{on chip | Illumina Human 1M}}