Salivary EGF, which seems also regulated by dietary inorganic iodine, plays an important physiological role in the maintenance of oral (and gastro-oesophageal) tissue integrity, and, on the other hand, iodine is effective in prevention of dental caries and oral health. Pathophysiology
Teeth are bathed in saliva and have a coating of bacteria on them (biofilm) that continually forms. The development of biofilm begins with pellicle formation. Pellicle is an acellular proteinaceous film which covers the teeth. Bacteria colonize on the teeth by adhering to the pellicle-coated surface. Over time, a mature biofilm is formed and this create a cariogenic environment on the tooth surface. The minerals in the hard tissues of the teeth (enamel, dentin and cementum) are constantly undergoing processes of demineralization and remineralization. Dental caries results when the demineralization rate is faster than the remineralization and there is net mineral loss. This happens when there is an ecologic shift within the dental biofilm, from a balanced population of micro-organisms to a population that produce acids and can survive in an acid environment. Enamel
Tooth enamel is a highly mineralized acellular tissue, and caries act upon it through a chemical process brought on by the acidic environment produced by bacteria. As the bacteria consume the sugar and use it for their own energy, they produce lactic acid. The effects of this process include the demineralization of crystals in the enamel, caused by acids, over time until the bacteria physically penetrate the dentin.
Costello syndrome is caused by mutations in HRAS. Mutations that cause Noonan syndrome have been found in PTPN11 and SOS1.The relative severity of CFC when compared to Noonan syndrome may reflect the position in the biochemical pathway occupied by the affected genes. Shp2, the protein product of the PTPN11 gene, appears to regulate the MAP kinase pathway at or above the level of SOS1. SOS1 in turn regulates the activities of RAS, RAF, MEK, ERK, and p90RSK. SOS1 has been demonstrated to be a target of negative feedback by ERK and p90RSK.Thus, any activating mutation downstream of SOS1 may be subject to less regulation that might mitigate the consequence of such mutations, giving rise to the phenotypic differences seen between these syndromes. Diagnosis
Management
References
External links

CFC Syndrome at Genetics Home Reference
GeneReview/UW/NIH entry on CFC