The hypodermis is the innermost and thickest layer of the skin. It invaginates into the dermis and is attached to the latter, immediately above it, by collagen and elastin fibres. It is essentially composed of a type of cells specialised in accumulating and storing fats, known as adipocytes.
Fatal familial insomnia Fatal familial insomnia (FFI) is a very rare, autosomal dominant inherited, disease of the brain. It is caused by a mutation in a protein called prion protein (PrP): asparagine-178 is replaced by aspartic acid.
Idiopathic hypersomnia is a rare condition characterized by episodes or extreme sleepiness that occur for no identifiable reason (idiopathic). Episodes may be chronic or constant. The disorder differs from narcolepsy in that affected individuals do not experience sudden sleep episodes or develop cataplexy.