Conversion events in the CYP2A13 gene. The detected conversions are mapped in the human CYP2A13 gene region, hg19.chr19:41,594,377-41,601,846. Green boxes represent exons, and blue lines indicate donor sequences which correspond to the positions of converted regions in the CYP2A13 gene. The numbers on the blue lines indicate the chromosomal positions of the donors in kilobases (kb). Blue boxes represent exons in the human CYP2A7 gene, which is one of the donors. The six non-synonymous SNPs indicated by black vertical bars on the exons have mutant alleles that share the same nucleotides as the donor sequences. For example, for the Arg257Cys SNP, the mutant, minor allele is Cys (TGC) in the human population, and the donor sequence at that position is also TGC. Arg25Gln and Arg257Cys (in red) are known to be associated with metabolic activity of a tobacco-specific carcinogen.