Amelogenesis imperfecta presents with abnormal formation of the enamel

Tooth enamel

Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

 or external layer of teeth. Enamel is composed mostly of mineral, that is formed and regulated by the proteins in it. Amelogenesis imperfecta is due to the malfunction of the proteins in the enamel: ameloblastin

Ameloblastin

Ameloblastin, also known as amelin, is a gene-specific protein found in tooth enamel. Although less than 5% of enamel consists of protein, ameloblastins comprise 5%-10% of all enamel protein. This protein is formed by ameloblasts during the early secretory to late maturation stages of amelogenesis...

, enamelin

Enamelin

Enamelin was described in older literature as an EDTA soluble enamel protein. It accounts for the organic portion of enamel, which represents 4% of enamel's mass. It turned out in recent research to be albumin derived from blood contamination....

, tuftelin

Tuftelin

Tuftelin is an acidic phosphorylated glycoprotein found in tooth enamel. In humans, the Tuftelin protein is encoded by the TUFT1 gene.- Function :This protein is formed for a short time during amelogenesis...

 and amelogenin

Amelogenin

Amelogenin is a protein found in developing tooth enamel, and it belongs to a family of extracellular matrix proteins. Developing enamel contains about 30% protein, and 90% of this is amelogenins...

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People afflicted with amelogenesis imperfecta have teeth with abnormal color: yellow, brown or grey.