The core protein of a major corneal keratan sulfate proteoglycan is encoded by the KERA gene, located on chromosome 12q21.33.  KERA is expressed mainly in the cornea and sclera, and it is also expressed, at lower levels, in the skin, ligaments, cartilage, arteries, and striated muscles.  Keratan sulfate proteoglycan protein may play an important role in developing and maintaining corneal transparency and in forming the structure of the stromal matrix.