a) The number of somatic mutations discovered from each paired NPC case subjected to WES and key clinical parameters (Supplementary Table 2a) clustered according to the clinical stage. Indel, insertion or deletion. (b) Trinucleotide contexts of somatic mutations occurring at cytosine nucleotides in NPC. The font size of the nucleotides at the 3′ and 5′ positions is proportional to their frequencies (Supplementary Fig. 3b). 