Background：

Proteins of the matrix metalloproteinase (MMP) family are involved in the breakdown of extracellular matrix in normal physiological processes， such as embryonic development， reproduction， and tissue remodeling， as well as in disease processes， such as arthritis and metastasis. Most MMP’s are secreted as inactive proproteins which are activated when cleaved by extracellular proteinases. The protein encoded by this gene degrades amelogenin， the major protein component of dental enamel matrix， and thus thought to play a role in tooth enamel formation. A mutation in this gene， which alters the normal splice pattern and results in premature termination of the encoded protein， has been associated with amelogenesis imperfecta. This gene is part of a cluster of MMP genes located on chromosome 11q22.3.