Matrix Metalloproteinase 20

Alternative Names

  • MMP20
  • Enamelysin
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OMIM Number

604629

Gene Map Locus
11q22.2

Description

The MMP20 protein belongs to the matrix metalloproteinase (MMP) family of proteins.  These proteins are involved in the breakdown of extracellular matrix in normal processes, such as embryonic development, reproduction, and tissue remodeling.  The MMP20 gene codes for a tooth-specific matrix metalloproteinase-20, which functions by degrading amelogenin, which is the major protein component of dental enamel matrix.  Therefore, mutations in this gene contribute to the abnormal formation of tooth enamel.  This gene is expressed in secretory stage ameloblasts, and the expressed protein plays a major role in allowing the enamel crystallites to grow in width and thickness.  MMP20 might also play a role in facilitating ameloblast movement in rows necessary to form mammalian rod patterns. 

Mutations in MMP20 are implicated in a form of Amelogenesis Imperfecta (AI2A2) as well as in age related macular degeneration.

Molecular Genetics

The MMP20 gene is located on the long arm of chromosome 11, along with a cluster of other MMP genes.  The gene consists of 10 exons and spans a length of about 48 Kb.  The encoded protein, also known as enamelysin, consists of 483 amino acid residues and has a molecular mass of 54 KDa.  Like other matrix metalloproteinases, MMP20 is also organized into a signal peptide, a prodomain with the conserved motif PRCGVPD, a catalytic domain with a Zn-binding site, and a COOH-terminal fragment. 

Epidemiology in the Arab World

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Other Reports

Saudi Arabia

Shahid et al., (2016) studied 21 Saudi Arabian families having 41 patients with non-syndromic forms of tooth agenesis.  DNA was isolated from peripheral blood samples and all exons and exon-intron boundaries of MSX1, PAX9, and MMP20 genes were sequenced.  Only one mutation in the MMP20 gene (c.66A>C; p.Lys18Thr) was identified in the study.  This mutation was found in 16 patients as well as in 10% of controls.  This mutation that lies in the first 22 amino acids forming the signal peptide of the protein was predicted to affect the translocation of the mature protein.  Half of the patients with mutations in the MMP20 gene were also found to have mutations in the other investigated genes.  

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