SNP Shot: Genomic Insights

Schwannomatosis is a condition where multiple benign tumors, called schwannomas, develop on nerves. These tumors arise from uncontrolled growth of Schwann cells, which normally create a protective coating around nerves.

Symptoms of schwannomatosis typically begin in early adulthood. Persistent pain is the most frequent symptom, and it can occur anywhere in the body. Sometimes, pain is experienced even in areas without detectable tumors. The intensity of the pain can vary from mild to severe and can be challenging to treat. Other symptoms depend on the tumor locations and the affected nerves. These can include numbness, weakness, tingling sensations, and headaches. Importantly, schwannomatosis does not typically shorten a person's lifespan.

Schwannomatosis is often classified as a type of neurofibromatosis, a group of conditions characterized by tumor growth in the nervous system. The other two types are neurofibromatosis type 1 and neurofibromatosis type 2. Schwannomatosis can resemble neurofibromatosis type 2, but it rarely involves vestibular schwannomas (tumors of the inner ear), which are characteristic of neurofibromatosis type 2. Other tumor types common in the other forms of neurofibromatosis are much less frequent in schwannomatosis.

Inheritance:

Most schwannomatosis cases occur sporadically, meaning they arise in individuals with no family history of the disorder. Some sporadic cases involve mutations in the SMARCB1 or LZTR1 genes, but in many, the cause is unknown. Approximately 15-25% of schwannomatosis cases are familial, running in families. These familial cases follow an autosomal dominant inheritance pattern. This means that inheriting a mutation in just one copy of the SMARCB1 or LZTR1 gene in each cell significantly raises the risk of developing schwannomas. However, some individuals with a mutated gene may never develop tumors, a phenomenon known as reduced penetrance.