From the present and other studies, patients with V950 M, R978C, G992R, D874V mutations in one NPC1 allele have so far shown an adolescent/adult neurological form of NP-C, even in association with a very severe allele (e.g., in patients 3, 6, 7, 8, 11, 16, 29, 31, 32, 33, 36 and 46) [6, 21, 51, 52]. This evidence concerns the gene NPC1 and nasopharyngeal carcinoma.