Consistently, radiation-treated Ptch1+/−p53∆E5-6/∆E5-6 or Ptch1+/−p53∆E5-6/R172P mice developed SHH-MBs with complete penetrance, median survival, p53 expression, and proliferation frequency comparable to untreated SHH-MBs (Figure 3D and E; Supplementary Figure S4E and F). The gene discussed is PTCH1; the disease is Mobius syndrome.