Human CYP3A5*9 allele is located in the vicinity of 7q21.1 and is approximately 32 kb in length. This allele, a variant form of the human CYP3A5 wild-type allele, encodes cytochrome P450 3A5*9 protein. The CYP3A5*9 allele exhibits a clinically-relevant SNP (g.19386G>A) in exon 10 that results in an A337T coding change. This alteration in protein sequence decreases the enzymatic activity of the cytochrome P450 3A5*9 protein. [ ]