Molecular analysis on the parental NPC1 genes of the deceased patient (Patient 2) revealed in both the same splicing mutation (IVS23 + 3insT). Consequently, homozygosity for an IVS23 + 3insT mutation was indirectly disclosed to be Patient’s 2 genetic cause of the NPC phenotype. Here, NPC1 is linked to nasopharyngeal carcinoma.