Finally, we show that biallelic inactivation of Smarcb1 and Nf2 in SCs results in benign schwannoma, and not in RT, thus re-emphasizing the necessary and sufficient role of NF2 loss in SC tumorigenesis, in both neurofibromatosis type 2 (NF2) and schwannomatosis, and the existence of a critical developmental risk period for SMARCB1-deficient RTs to occur. The gene discussed is SMARCB1; the disease is schwannomatosis.