NPC1 and nasopharyngeal carcinoma: Biallelic mutations in one of two genes (NPC1 and NPC2) result in NPC, although the two complementation groups appear biochemically indistinguishable and the majority of cases (approximately 95%) occur from DNA-variants in NPC1 (Carstea et al., 1997; Naureckiene et al., 2000; Ikonen and Hölttä-Vuori, 2004), which, to date, is associated with hundreds of pathogenic mutations.