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Inherited condition that affects the enamel of the teeth, making them soft and thin. The teeth are easily damaged and appear yellow because the dentin is visible through the thin enamel.

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1:20,000 live births for the most common form (enamel hypocalcification, see Clinical Aspects). Most often autosomal dominant inheritance, with the defect mapped to 4q21 and 4q11-q21. However, some forms are X-linked dominant with the defect located on Xp22 and Xq22-28, and other forms are autosomal recessive.

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Both the primary and the secondary dentitions are affected. Two types of amelogenesis imperfecta have been described:

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  1. 1. Hereditary enamel hypocalcification, where the amount of enamel is normal but the degree of calcification is insufficient. This is the most frequent type of enamel dysplasia.

  2. 2. Hereditary enamel hypoplasia, where the quality of the enamel is normal but the quantity is deficient.

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The enamel defect becomes obvious soon after the teeth erupt and is lost soon thereafter. In the case of enamel hypocalcification, the enamel can easily be scraped off the teeth. Anterior open bite is present in approximately two thirds of patients. The clinical course in the autosomal recessive form is more severe than in the other forms. This can be confirmed by radiologic and histologic findings.

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Obtain history and document loose teeth. Teeth are soft and may be easily damaged, especially during laryngoscopy.

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Tricho-Dento-Osseous (TDO) Syndrome: Features of this autosomal dominant inherited disorder are enamel hypoplasia and hypocalcification, combined with curly, dry hair.

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Amelogenesis Imperfecta, Hypomaturation-Hypoplasia-Type with Taurodontism Syndrome: Clinically very similar but genetically slightly different. The dental changes seen in this syndrome are identical to those occurring in trichodentoosseous syndrome, but hair changes and osteosclerosis are absent.

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Laryngo-Onycho-Cutaneous (LOC) Syndrome: Severe progressive multisystem disorder involving the skin (dermal granula and ulcerations) and larynx (vocal cord granuloma), often lethal during childhood.

Backman B, Holmgren G: Amelogenesis imperfecta: A genetic study. Hum Hered 38:189, 1988.  [PubMed: 3169793]
Rajpar MH, Harley K, Laing C, et al: Mutation of the gene encoding the enamel-specific protein, enamelin, causes autosomal-dominant amelogenesis imperfecta. Hum Mol Genet 10:1673, 2001.  [PubMed: 11487571]

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