SOX2 (Transcription factor SOX-2) 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. Defects in Sox2 are the cause of microphthalmia syndromic type 3 (MCOPS3). Microphthalmia is a clinically heterogeneous disorder of eye formation, ranging from small size of a single eye to complete bilateral absence of ocular tissues (anophthalmia). In many cases, microphthalmia/anophthalmia occurs in association with syndromes that include non-ocular abnormalities. POU5F1/OCT4, Sox2, MYC/c-Myc and KLF4 are the four Yamanaka factors. When combined, these factors are sufficient to reprogram differentiated cells to an embryonic-like state designated iPS (induced pluripotent stem) cells. iPS cells exhibit the morphology and growth properties of ES cells and express ES cell marker genes.