Genetic tumor syndromes, such as Li-Fraumeni syndrome, Lynch syndrome, DICER1 syndrome, Hereditary Diffuse Gastric Cancer, Neurofibromatosis type 1, Peutz-Jeghers syndrome, PTEN hamartoma tumor syndrome, Tuberous Sclerosis, and pathogenic variants in NBN and SMARCA4, illustrate the genetic and phenotypic heterogeneity underlying inherited breast and gynecologic malignancies. Here, NBN is linked to Familial gastric cancer.