Rhabdomyosarcomas do not contain mutations in the DNA binding domains of myogenic transcription factors.

Skeletal myogenesis is regulated by a group of transcription factors (MyoD, myogenin, myf5, and myf6) that are "basic helix-loop-helix" proteins that bind to the promoters of muscle-specific genes and promote their expression. We have previously shown that after a mutation of Leu122 to Arg the DNA binding basic domain of MyoD confers c-myc-like functional characteristics to the protein. In this study we used single-strand conformation polymorphism analysis to determine whether such mutations occur naturally in rhabdomyosarcomas. We have found that the basic domains of all the myogenic factors remain unaltered in rhabdomyosarcomas. Selection against such mutations may be the result of functional redundancy of these myogenic transcription factors.