a. Multiple sequence alignment showing exon 9 of CYP2A6*1 (NG_008377.1: 11574–11652; GRCh37: 41349779–41349701), CYP2A6*5, and WT CYP2A7 (NG_007960.1: 11982–12060; GRCh37: 41381676–41381598). Vertical dashes between alignments indicate identity, while dots indicate non-identical sequence. b. Alignment of CYP2A6*5 reads with and without masking of CYP2A7. Without masking of CYP2A7, CYP2A6*5 reads are interpreted by the read aligner as CYP2A7, and are incorrectly aligned to exon 9 of CYP2A7 during .bam file generation. Masking of CYP2A7 forces alignment of CYP2A6*5 reads to CYP2A6, allowing for accurate genotype calling.