In this study, Moura et al., analyzed the genomes of two patients with distinct genotypically and phenotypically gastrointestinal stromal tumors (GIST) to identify shared genetic variations that might contribute to tumor development. The authors discovered that both patients had identical deletions in two genes, CFHR1 and CFHR3, which were present in the patient’s normal cells, not just in the tumor cells, suggesting that these alterations might increase the risk of developing GISTs. While more research is needed to confirm the role of these genetic changes, this study provides new clues about potential inherited factors in GIST formation. (By Dr. David S. Moura, https://jmg.bmj.com/content/early/2024/08/17/jmg-2024-110109 )