SMARCB1

(redirected from INI1)

SMARCB1

A gene on chromosome 22q11.23 that encodes a core component of the ATP-dependent chromatin-remodelling BAF (hSWI/SNF) complex, which plays key roles in cell proliferation and differentiation and has antiviral and anti-tumour activity.

Molecular pathology
Defects in SMARCB1 rhabdoid tumour predisposition syndrome type 1, schwannomatosis and mental retardation, autosomal dominant type 1.
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References in periodicals archive ?
(60) The diagnosis of HPV-related multiphenotypic sinonasal carcinoma requires HPV-specific testing as part of the tumor definition (Figure 4, B), (61) whereas for the diagnosis of SMARCB1 (INI1)-deficient carcinoma, loss of nuclear immunohistochemical staining for INI1 is required.
The nuclei of neoplastic cells showed intact INI1 expression (Table 1).
(3) Our patient's immunohistochemistry demonstrated S-100 protein positivity and loss of INI1, consistent with EMPNST.
There was a diffuse nuclear staining for INI1. Alpha-smooth muscle actin and desmin immunostainings were negative.
A panel comprising PAX8, p63, and INI1 is most optimal for distinguishing RMC from transitional cell carcinoma and collecting duct carcinoma, as all these tumors show a similar staining pattern with CK7 and vimentin.
Following delineation of the roles of SMARCB1 (INI1) in different neoplasms [3], SMARCA4 (BRG1) on chromosome 19p13.2 has been recently increasingly recognized as the main or sole molecular driver event in SMARCB1-intact rhabdoid malignancies including in particular the vast majority of small cell carcinomas of ovary, hypercalcemic type (SCCOHT) [4].
[1] However, specific immunohistological markers, in particular INI1, have made it possible to differentiate these tumours from PNETs in cases where primitive cells predominate.
Chemotherapy consisted in the European Soft Tissue Sarcoma Study Group (EpSSG) extracranial rhabdoid tumor protocol (carboplatin, vincristine, cyclophosphamide with doxorubicin, ifosfamide, and etoposide) because institutional pathologic examination concluded to a rhabdoid tumor on reticular pattern of rhabdoid-like cells with absence of INI1 expression.
The common genetic basis for rhabdoid tumours is a deletion and/or mutation of the INI1 gene on chromosome 22 (22q11), inactivating the tumour suppressor gene SMARCB1, though these tumours can lack this mutation as seen in this case.[sup.1]
Absence of INI1 is valuable in confirming the diagnosis of renal or extrarenal MRT versus other tumors with focal rhabdoid appearance [89].
officinarum [POC.sub.LS] (%) 30.11 16.15 [POC.sub.R] (%) 69.88 83.82 [k.sub.T] ([day.sup.-1]) 1.071 0.954 [k.sub.4] ([day.sup.-1]) 0.005 0.007 [r.sup.2] 0.98 0.98 DOC (%) 22.36 10.07 [k.sub.3] ([day.sup.-1]) 0.062 0.025 [r.sup.2] 0.96 0.78 INI1 (%) * 7.74 6.08 [k.sub.1] ([day.sup.-1]) ** 0.275 0.359 [k.sub.2] ([day.sup.-1]) ** 0.796 0.594 [t.sub.1/2 (kT)] (day) 0.647 0.727 [t.sub.1/2 (k1)] (day) 2.515 1.929 [t.sub.1/2 (k2)] (day) 0.871 1.166 [t.sub.1/2 (k3)] (day) 11.124 27.326 [t.sub.1/2 (k4)] (day) 125.798 97.059 (*) Values proportional to the formation of I[N.sub.1]; (**)Values estimated by the difference between [POC.sub.LS] and DOC.