Rapp–Hodgkin syndrome was formerly thought to be a unique autosomal dominant disorder due to a P63 gene mutation. However, it was recently shown to the same disease as Hay-Wells syndrome. Rapp–Hodgkin syndrome was formerly thought to be a unique autosomal dominant disorder due to a P63 gene mutation. However, it was recently shown to the same disease as Hay-Wells syndrome. It was first characterized in 1968.