Dentinogenesis Imperfecta
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What is dentinogenesis imperfecta?Dentinogenesis imperfecta is a disorder of tooth development. This condition causes teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent. Teeth are also weaker than normal, making them prone to rapid wear, breakage, and loss. These problems can affect both primary (baby) teeth and permanent teeth. Researchers have described three types of dentinogenesis imperfecta with similar dental abnormalities. Type I occurs in people who have osteogenesis imperfecta, a genetic condition in which bones are brittle and easily broken. Dentinogenesis imperfecta type II and type III usually occur in people without other inherited disorders. A few families with type II have progressive hearing loss in addition to dental abnormalities. Type III dentinogenesis imperfecta was first identified in a population from Brandywine, Maryland. Researchers now believe that type II and type III may be the same disorder. How common is dentinogenesis imperfecta?Dentinogenesis imperfecta affects an estimated 1 in 6,000 to 8,000 people. What genes are related to dentinogenesis imperfecta?Mutations in the DSPP gene cause dentinogenesis imperfecta. Mutations in the DSPP gene have been identified in people with type II and type III dentinogenesis imperfecta. Type I occurs as part of osteogenesis imperfecta, which is caused by mutations in one of several other genes. The DSPP gene provides instructions for making three proteins that are essential for normal tooth development. These proteins are involved in the formation of dentin, which is a bone-like substance that makes up the protective middle layer of each tooth. Mutations in the DSPP gene may affect the proteins made by the gene, leading to the production of abnormally soft dentin. Teeth with defective dentin are discolored, weak, and more likely to decay and break. It remains unclear how DSPP mutations lead to hearing loss in some families with dentinogenesis type II. How do people inherit dentinogenesis imperfecta?This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.
Source: National Institutes of Health
Study results from Ghent University provide new insights into life sciences genetics
2007 MAR 13 -- Research findings, "Abnormal dentin structure in two novel gene mutations [COL1A1, Arg134Cys] and [ADAMTS2, Trp795-to-ter] causing rare type I collagen disorders," are discussed in a new report. "Histological and ultrastructural observations of dentin of two patients affected with rare types of type I collagen disorders are presented. In the first case, a homozygous nonsense mutation in ADAMTS2 (substitution of a codon for tryptophan by a stopcodon) causes type VIIC Ehlers-Danlos syndrome (EDS) with multiple tooth agenesis and focal dysplastic dentin defects," scientists in Ghent, Belgium report. "In the second case, a missense mutation in COL1A1 (substitution of arginine by cysteine) results in a type I EDS phenotype with clinically normal-appearing dentition. Tooth samples are investigated by using light microscopy (LM), transmission electron microscopy (TEM) and immunostaining for types I and III collagen, and tenascin. These are compared with samples from patients with types III and IV osteogenesis imperfecta (OI) in association with dentinogenesis imperfecta (DI), showing a consistently abnormal appearance of the dentin in all specimens, with variations being primarily those of degree of change. Similarities in histological changes include the alternating presence of normal and severe pathological areas in primary and secondary dentin, the latter being characterized by large canal-like structures in atubular areas. Ultrastructural evidence of pathological dentinogenesis include abnormal distribution, size and organization of collagen fibers, which may also be found in clinically unaffected teeth. The histological and ultrastructural changes seen can be explained on the basis of odontoblast dysfunction which may be secondary to the collagen defect, interfering with different levels of odontoblast cell function and intercellular communication," wrote Coster P.J. De and colleagues, Ghent University. The researchers concluded: "These observations on (ultra).tructural dentin defects associated with the two novel gene mutations are the first ever reported." De and colleagues published their study in Archives of Oral Biology (Abnormal dentin structure in two novel gene mutations [COL1A1, Arg134Cys] and [ADAMTS2, Trp795-to-ter] causing rare type I collagen disorders. Archives of Oral Biology, 2007;52(2):101-9). For additional information, contact P.J. De Coster, Paecamed Research, Dept. of Paediatric Dentistry and Special Care, Ghent University, Ghent, Belgium. The publisher's contact information for the journal Archives of Oral Biology is: Pergamon-Elsevier Science Ltd., the Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, England. Keywords: Belgium, Ghent, Life Sciences Genetics. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2007, Life Science Weekly via NewsRx.com.
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