The association of severe encephalopathy and question mark ear is highly suggestive of loss of MEF2C function.

Auriculocondylar syndrome and isolated question mark ear result from dysregulation of the endothelin 1-endothelin receptor type A signaling pathway. Animal models have highlighted the role of the transcription factor MEF2C as an effector of this pathway. We report heterozygous MEF2C loss-of-function as a possible cause of question mark ear associated with intellectual deficiency.