Furthermore, immunofluorescence (IF) assays for XAF1 protein expression were performed in paraffin-embedded surgically resected tumor tissues from patients with GI cancer, with or without the mutation.<h4>Results</h4>In a family with GI cancer, we identified a mutation of <i>XAF1</i> (c.454+1372G>A), which is a nonsense mutation in Exon 4b that results in a truncated XAF1 Isoform 5. The gene discussed is XAF1; the disease is neoplasm.