SMARCB1 sinus cancer is a rare and highly aggressive and malignant tumor of your nasal cavity and your paranasal sinuses, which is often characterized by the loss of the SMARCB1 INI-1 protein.
SMARCB1 sinus cancer often presents at an advanced stage with a poor prognosis, and it frequently so invades your skull base or orbit.
The symptoms of SMARCB1 sinus cancer are nosebleeds, headaches and nasal obstruction and is often mistaken for other cancer types, like sinonasal undifferentiated carcinoma.
Diagnosis of SMARCB1 sinus cancer requires immunohistochemistry to confirm the absence of the INI-1 protein.
The tumor cells often exhibit rhabdoid, plasmacytoid or basaloid features and there's no standard treatment for SMARCB1 sinus cancer, although options like surgery, radiotherapy and chemotherapy can help slow the progression of the SMARCB1 sinus cancer.
SMARCB1 sinus cancer is extremely rare, and accounts for only 1 percent of head cancers and neck cancers.
The causes of SMARCB1 cancer are mutations or deletions of the SMARCB1 gene, which is a vital tumor suppressor which regulates cell growth.
The loss of these SMARCB1 gene, often called INI1 or SNF5, disrupts your SWI/SNF chromatin remodeling complex that causes cells to grow uncontrollably and results in and leads to growth of aggressive tumors like rhabdoid tumors.
SMARCB1 is also hereditary in an autosomal dominant manner.
Being that SMARCB1 is hereditary in an autosomal dominant manner, it means that a single inherited copy of the mutated gene can cause the SMARCB1 condition.
These include SMARCB1-related schwannomatosis and rhabdoid tumor predisposition syndrome (RTPS1).
Although these can be inherited from a parent in a 50/50 chance, they often also occur as de novo or new mutations.
SMARCB1 is autosomal dominant, which means that only one parent needs to carry the mutation for a child to have a 50 percent change of inheriting SMARCB1.
Although not everyone who inherits the mutated SMARCB1 gene will develop SMARCB1 or the SMARCB1 tumor, which is a phenomenon that is known a reduced penetrance.
And a significant percentage of cases SMARCB1 or up to 30 percent for some schwannomatosis cases arise or come on spontaneously in a person with no prior family history.
And even germline SMARCB1 mutations are also linked rhabdoid tumor predisposition syndrome or aggressive childhood tumors and schwannomatosis tumors on the nerves.
Genetic counseling and testing are also highly recommended for families that have a history of these to determine their risks.
SMARCB1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily B member 1) is
a critical tumor suppressor gene located on chromosome 22q11.23.
And it also encodes the INI1 protein, a core subunit of the SWI/SNF chromatin remodeling complex, which regulates gene expression and cell differentiation.
The loss of SMARCB1 is a key driver in rare, aggressive cancers, including malignant rhabdoid tumors, epithelioid sarcoma, and renal medullary carcinoma.
SMARCB1 is also often referred to as INI1, BAF47, SNF5, or SMARCA4.
And s a part of the SWI/SNF complex, it also aids in repairing DNA and controlling cell growth and maintaining chromatin structure.
When both alleles are lost through biallelic inactivation, it leads to malignancy and is the defining feature of undifferentiated chordoma, sinonasal carcinoma, renal medullary carcinoma, epithelioid sarcoma and malignant rhabdoid tumors.
SMARCB1-deficient tumors often also show resistance to conventional treatments and have a poor prognosis, making them a target for epigenetic therapies like EZH2 inhibitors (e.g., tazemetostat).