, also known as 558C>A or F186L, is a SNP in the CYP1A2
gene. In a CYP database
, it is listed as defining the CYP1A2*11 allele.
23andMe and opensnp show A as more common. dbSNP shows C as the reference, and A as the variant, but no population frequency information is provided. This SNP was originally observed in a Japanese population at a frequency of 0.3%; in an Italian study of 500 healthy individuals, it was not observed.[PMID 17603224]
[PMID 14563787] claims that A is the variant, and that it defined the CYP1A2*11 allele with a Vmax approximately 5% of that of the CYP1A2 wild type, and reduced enzymatic activity. Two subsequent theoretical studies provide hypotheses for why this change results in lowered activity.[PMID 21598960],[PMID 24464701]