Inherited defects in DNA repair pathways, such as germline mutations in BRCA1 or Fanconi anemia pathway genes that normally repair double‐strand breaks and DNA cross‐links, lead to the accumulation of mutations that impair stem cell function and promote tumorigenesis (Dietlein et al, 2014; Ma et al, 2018). This evidence concerns the gene BRCA1 and Fanconi anemia.