Endocrine signalling is thought to be an important factor in cNF growth and development.30,86,87 This hypothesis is underpinned by the observation of the rapid onset and growth of neurofibromas that can occur during puberty and pregnancy,17,86,88,89 and there are increasing amounts of molecular data to support this idea. The gene discussed is NPHS1; the disease is plexiform neurofibroma.