Amelogenesis imperfecta (AI) is a congenital disorder which presents with a rare abnormal formation of the enamel or external layer of the crown of teeth, unrelated to any systemic or generalized conditions. 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, enamelin, tuftelin and amelogenin) as a result of abnormal enamel formation via amelogenesis.People with amelogenesis imperfecta may have teeth with abnormal color: yellow, brown or grey; this disorder can affect any number of teeth of both dentitions. Enamel hypoplasia manifests in a variety of ways depending on the type of AI an individual has (see below), with pitting and plane-form defects common. The teeth have a higher risk for dental cavities and are hypersensitive to temperature changes as well as rapid attrition, excessive calculus deposition, and gingival hyperplasia. The earliest known case of AI is in an extinct hominid species called Paranthropus robustus, with over a third of individuals displaying this condition. Genetics
Several gene expression is needed for enamel formation where the relevant matrix proteins & proteinases are transcribed for regular crystal growth & enamel mineralization.Mutations in the AMELX, ENAM, MMP20, KLK-4, FAM83H, WDR72, C4orf26, SLC24A4 LAMB3 and ITGB6 genes have been found to cause amelogenesis imperfecta (non-syndromic form). AMELX and ENAM encode extracellular matrix proteins of the developing tooth enamel and KLK-4 and MMP20 encode proteases that help degrade organic matter from the enamel matrix during the maturation stage of amelogenesis.
Parents who are carriers of the defective genes show no symptoms but their children have a 25% chance of having CIE.There are several genetic faults which can produce CIE. Known genes involved include TGM1, ALOX12B, ALOXE3, NIPAL4, ABCA12, CYP4F22, LIPN, CERS3, PNPLA1, ST14, and CASP14. Diagnosis
Diagnosis of this condition is done via:
Sequencing of genes- TG1,ALOXE3, ALOX12B, NIPAL4,CYP4F2, CERS3, LIPN etc..Measuring insitu TG1 activity in cryostat sectionelectron microscopy- cholesterol clefts in stratum corneum

Treatment
See also
Ichthyosis
Lamellar ichthyosis
Collodion baby
List of cutaneous conditions

References
External links
GeneReviews/NCBI/NIH/UW entry on Autosomal Recessive Congenital Ichthyosis