The penetrance of GPVs causing inherited cancer susceptibility can vary with different mutations in the same gene, which can cause altered degrees of cancer susceptibility and tumour spectrum and even different clinical phenotypes, for example, as noted above with RET GPVs in MEN2 and mutations in TGFBR1, where missense mutations can cause a Marfanoid‐like vasculopathy or Loeys–Dietz syndrome, but others (e.g., truncations or missense mutations in specific domains of the gene) can cause Ferguson–Smith syndrome (self‐healing squamous epithelioma) (Goudie et al. This evidence concerns the gene RET and cancer.