Since LOH indicates an obligate pathway to schwannoma mediated by LZTR1/SMARCB1, this suggests that further potentially pathogenic LZTR1 variants may not be the cause of schwannomatosis and that additional tumor data are needed to confirm the causality of a novel LZTR1 variant found in a schwannomatosis patient. The gene discussed is SMARCB1; the disease is neoplasm.