NCIt definition : Human CYP2C19*1 allele is located within 10q24.1-q24.3 and is approximately 90 kb
in length. This allele, a variant form of the CYP2C19 wild-type allele, encodes cytochrome
P450 2C19*1 protein. There are multiple haplotypes of this allele. The nucleotide
sequence of CYP2C19*1A is identical to that of the wild-type allele and exhibits no
mutations. CYP2C19*1B and CYP2C19*1C both exhibit a SNP (c.991A G) in exon 7 that
results in an I331V coding change. This alteration in protein sequence has no effect
on the enzymatic activity of the corresponding cytochrome P450 2C19*1 proteins.;