Test Catalog

Test ID: BRG1    
BRG1 (SMARCA4) Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing ovarian small cell carcinoma of hypercalcemic type (SCCOHT)

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

BRG1 (SMARCA4) is a member of the switch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complex. Biallelic mutations in BRG1 (SMARCA4) have been reported in ovarian small cell carcinoma of hypercalcemic type (SCCOHT), amongst other tumors. Tumors with these mutations demonstrate a loss of BRG1 protein expression in the nucleus. SCCOHT is difficult to diagnose and loss of BRG1 expression can help in differentiating SSCOHT from its mimics including other primary or metastatic tumors of the ovaries.

Interpretation Provides information to assist in interpretation of the test results

This test does not include pathologist interpretation; only technical performance of the stain is performed. If an interpretation is required, order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Loss of BRG1 expression as determined by immunohistochemistry is not able to differentiate between germline and somatic mutations.


Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen-dependent. Best practice is for paraffin sections to be cut within 6 weeks.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Clarke BA, Witkowski L, Ton Nu TN, et al: Loss of SMARCA4 (BRG1) Protein Expression by Immunohistochemistry in Small Cell Carcinoma of the Ovary, Hypercalcemic Type Distinguishes these Tumors from their Mimics. Histopathology 2016 Apr 21

2. Conlon N, Silva A, Guerra E, et al: Loss of SMARCA4 Expression Is Both Sensitive and Specific for the Diagnosis of Small Cell Carcinoma of Ovary, Hypercalcemic Type. Am J Pathol 2016;40:395-403

3. Karanian-Philippe M, Velasco V, Longy M, et al: SMARCA4 (BRG1) Loss of Expression Is a Useful Marker for the Diagnosis of Ovarian Small Cell Carcinoma of the Hypercalcemic Type (Ovarian Rhabdoid Tumor). Am J Surg Pathol 2015;39:1197-1205

4. Ramos P, Karnezls A, Craig D, et al: Small Cell Carcinoma of the Ovary, Hypercalcemic Type, Displays Frequent Inactivating Germline and Somatic Mutations in SMARCA4. Nat Genet 2014;46(5):427-430