Human CYP1A2*7 allele is located within 15q24 and is approximately 8 kb in length. This allele, a variant form of the CYP1A2 wild-type allele, encodes cytochrome P450 1A2*7 protein. The CYP1A2*7 allele exhibits a clinically-relevant SNP (g.3534G>A) in the 5' splice-site consensus sequence of intron 6 that is predicted to result in abnormal mRNA splicing. This alteration decreases the in vivo enzymatic activity of the cytochrome P450 1A2*7 protein. [ ]