Loss of SMARCA4/BRG1 expression plays a vital role in the diagnosis of SMARCA4-UT; however, it is important to note that approximately 5% of conventional NSCLC may also demonstrate deficiency in SMARCA4 and some SMARCA4-UT cases show a severe reduction of SMARCA4/BRG1 expression instead of a complete loss [1]. The gene discussed is SMARCA4; the disease is non-small cell lung carcinoma.