Type VII collagen deficiency causes defective tooth enamel formation due to poor differentiation of ameloblasts.

[dystrophic epidermolysis bullosa]

Recessive dystrophic epidermolysis bullosa (RDEB ) is caused by mutations in the gene encoding type VII collagen (COL 7 ), a major component of anchoring fibrils in the epidermal basement membrane zone . Patients with RDEB present a low oral hygiene index and prevalent tooth abnormalities with caries . We examined the tooth enamel structure of an RDEB patient by scanning electron microscopy . It showed irregular enamel prisms , indicating structural enamel defects . To elucidate the pathomechanisms of enamel defects due to COL 7 deficiency , we investigated tooth formation in Col 7 a 1 (-/-) and COL 7 -rescued humanized mice that we have established . The enamel from Col 7 a 1 (-/-) mice had normal surface structure . The enamel calcification and chemical composition of Col 7 a 1 (-/-) mice were similar to those of the wild type . However , transverse sections of teeth from the Col 7 a 1 (-/-) mice showed irregular enamel prisms , which were also observed in the RDEB patient . Furthermore , the Col 7 a 1 (-/-) mice teeth had poorly differentiated ameloblasts , lacking normal enamel protein-secreting Tomes ' processes , and showed reduced mRNA expression of amelogenin and other enamel -related molecules . These enamel abnormalities were corrected in the COL 7 -rescued humanized mice expressing a human COL 7 A 1 transgene . These findings suggest that COL 7 regulates ameloblast differentiation and is essential for the formation of Tomes ' processes . Collectively , COL 7 deficiency is thought to disrupt epithelial-mesenchymal interactions , leading to defective ameloblast differentiation and enamel malformation in RDEB patients .

Diseases
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Diseases presenting "low oral hygiene index" symptom

dystrophic epidermolysis bullosa

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