Through comprehensive genetic analysis, we hypothesized that in addition to <i>SMARCA4 (BRG1)</i> deficiency, other genetic changes might also be involved in the tumorigenesis of undifferentiated gallbladder cancer in this patient, particularly somatic mutations in the <i>CTNNB1, KRAS, PIK3CA, TP53, CREBBP</i>, and <i>FANCI</i> genes. This evidence concerns the gene PIK3CA and gallbladder cancer.