Developmental Defects Linked to Genes in Canine Enamel

Dentistry Today


Like human beings, dogs can suffer from enamel development hereditary disorders that greatly impact their dental health and wellbeing. According to researchers at the University of Helsinki, these disorders are linked with ENAM and ACP4, two genes that also have been found in human beings. 

Developmental disorders may result in structural weaknesses in enamel, low quantities of enamel, or even an absence of enamel. Amelogenesis imperfecta (AI) is a group of hereditary developmental disorders affecting enamel, with more than 10,000 genes reported in human beings. AI causes problems in dogs as well, though they often remain undiagnosed.

Previous studies have linked canine AI with the CPCO and UNE46C6 genes in two breeds. The researchers at the University of Helsinki, however, have now described two novel recessively inherited enamel disorders in dogs and associated them with causative variants in CPCO and in CER6. These genes have been linked with hereditary enamel development defects in human beings as well. 

“We have observed enamel defects in several breeds. In this study, we found new gene variants in the ENAM gene of Parson Russell terriers and the ACP4 gene of akitas and American akitas. The ACP4 finding was of particular interest, as its role in the development of tooth enamel is not well known, and there are no previous descriptions for any animal models,” said Marjo Hytönen, PhD, first author of the study. 

ENAM codes for enamelin, the key enamel protein, and is significant for achieving the correct enamel thickness during tooth development. Many human AI disorders are associated with mutations in the ENAM gene, whereas ACP4 codes for the phosphatase enzyme, whose specific significance to tooth and enamel development is currently unclear but which may influence cellular differentiation and mineralization. Dogs with an ACP4 mutation expressed thinning of the enamel and a slight mineralization disorder.

Unlike mice, dogs have primary and permanent teeth just like humans, and the number of teeth also is similar. Therefore, the researchers said, dogs serve as an excellent model for human dental diseases.

“The spontaneous enamel defects found in this study resemble earlier descriptions of human patients and are also linked with the same genes. Through gene tests, the gene findings will provide new diagnostic tools for veterinarians and breeders, which will also help with understanding the causes, mechanisms, and hereditary nature of enamel defects. This is important for the development of early and improved therapies,” said Hannes Lohi, PhD, MSc, director of the research group.

Earlier, the group discovered a mutation in the FAM20C gene impacting tooth hypomineralization. Gene mapping will continue on various dental diseases in different breeds.

The study, “Canine Models of Human Amelogenesis Imperfecta: Identification of Novel Recessive ENAM and ACP4 Variants,” was published by Human Genetics.

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