SOX 2 is also known as SRY related HMG BOX gene 2. All SOX proteins have a single HMG box and bind linear DNA in a sequence-specific manner, resulting in the bending of DNA through large angles. Bending causes the DNA helix to open for some distance, which may affect binding and interactions of other transcription factors. SOX 2 is a transcription factor that forms a trimeric complex with OCT4 on DNA and controls the expression of a number of genes involved in embryonic development such as YES1, FGF4, UTF1 and ZFP206. Critical for early embryogenesis and for embryonic stem cell pluripotency. SOX2 is required for stem-cell maintenance in the central nervous system, and also regulates gene expression in the stomach. Mutations in this gene have been associated with optic nerve hypoplasia and with syndromic microphthalmia, a severe form of structural eye malformation.