What causes Schwannomatosis ?
What causes schwannomatosis? Some cases of schwannomatosis are caused by changes (mutations) in the SMARCB1 or LZTR1 genes. SMARCB1 and LZTR1 are tumor suppressor genes, which means that they encode a protein that stops cells from growing and dividing too rapidly or in an uncontrolled way. Mutations in these genes result in abnormal proteins that are unable to carry out their normal roles. This contributes to the development of the many different types of tumors found in schwannomatosis. When schwannomatosis is caused by a mutation in SMARCB1 or LZTR1, the affected person is typically born with one mutated copy of the gene in each cell and is, therefore, genetically predisposed to develop the tumors associated with the condition. For a tumor to form, two copies of the gene must be altered. The mutation in the second copy of the gene is considered a somatic mutation because it occurs during a person's lifetime and is not inherited. In affected people without a mutation in SMARCB1 or LZTR1, the underlying cause of the condition is unknown.