{{is a|genotype}}
The effect of [[CYP2C9]] variants on drug metabolism cannot be predicted without considering [[CYP2C9*2]], defined as the common minor variant [[rs1799853(T)]] (NM_000771:c.430C>T, NP_000762:p.144R>C) that confers lower enzyme activity than the most common allele [[rs1799853(C)]] [http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs=1799853]  [PMID 8004131] [http://www.pharmgkb.org/search/annotatedGene/cyp2c9/].