Since Piotrowski et al. (2014) analysed a preselected group of patients and did not include those patients who, although fulfilling the diagnostic criteria for schwannomatosis, lacked biallelic NF2 inactivation in their tumours, the proportion of unexplained sporadic schwannomatosis cases caused by mutations in other as yet unidentified genes could be even higher. The gene discussed is NF2; the disease is neoplasm.