TNE by CYP2A6 diplotype. Diplotypes categories are defined by the functional activity of each allele as follows: N (no variant allele or *1A +*14); I (intermediate activity), *1H, *1A, *9, *17, *23; L (little or no activity), *4, *1A+2, *1H+2, *12, *1H+*7, *7. Alleles as described http://www.cypalleles.ki.se/cyp2a6.htm. From Murphy et al, Carcinogenesis (2016) 37 (3): 269–279. Used by permission of Oxford University Press.