ORPHA: 100032; DO: 0080243;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 4q13.3 | ?Amelogenesis imperfecta, type IIIB | 617607 | Autosomal dominant | 3 | AMTN | 610912 |
A number sign (#) is used with this entry because of evidence that hypomineralized amelogenesis imperfecta type IIIB (AI3B) is caused by heterozygous mutation in the amelotin gene (AMTN; 610912). One such family has been reported.
Hypomineralized amelogenesis imperfecta type IIIB (AI3B) is characterized by enamel that is reduced in mineral density and is thin, chipped, and absent in places (Smith et al., 2016).
Smith et al. (2016) described a 4-generation Costa Rican family segregating hypomineralized amelogenesis imperfecta. Examination of deciduous teeth from an affected individual showed reduced enamel mineral density. Enamel thickness was reduced; however, the authors noted this was possibly posteruptive tissue loss. Scanning electron microscopy showed areas of disturbed enamel structure, and the prismatic structure showed a 'gnarled' appearance.
The transmission pattern of AI3B in the family reported by Smith et al. (2016) was consistent with autosomal dominant inheritance.
In a Costa Rican family segregating autosomal dominant hypomineralized amelogenesis imperfecta, Smith et al. (2016) identified a heterozygous deletion/insertion mutation in the amelotin gene (610912.0001) that segregated with the phenotype in the family. The mutation was predicted to result in an in-frame deletion of 92 amino acids, shortening the protein from 209 to 117 amino acids. The mutation was not present in the Database of Genomic Variants. No functional studies were performed.
Smith, C. E. L., Murillo, G., Brookes, S. J., Poulter, J. A., Silva, S., Kirkham, J., Inglehearn, C. F., Mighell, A. J. Deletion of amelotin exons 3-6 is associated with amelogenesis imperfecta. Hum. Molec. Genet. 25: 3578-3587, 2016. [PubMed: 27412008] [Full Text: https://doi.org/10.1093/hmg/ddw203]