PTCH1 and embryonal rhabdomyosarcoma: The role of Hedgehog signalling in the genesis of RMS was first described in the Patched knockout mouse by Hahn et al. in 1998 [27] who reported that mice heterozygous for Ptch1 not only develop features consistent with Gorlin's syndrome, such as generalised overgrowth of the body and a variety of neural and skeletal abnormalities, but also have a high incidence of ERMS.