Amelogenesis imperfecta in Parson Russell Terrier

Amelogenesis imperfecta is a term for a disorder of tooth enamel formation. This disease leads to thinning and softening of tooth enamel, its rapid erosion and increased susceptibility to dental decay and damage. It is often manifested by brown spots and roughened tooth surfaces, and in young dogs, large gaps between the teeth are noticeable.

In Parson Russell Terriers, the cause is a missense mutation c.716C>T in the ENAM gene, which encodes enamelin, a protein essential for the formation of tooth enamel.

The mode of inheritance of the mutation is autosomal recessive. It is manifested only in an individual who inherited the mutated allele from both parents (recessive homozygous). A heterozygote is an individual who received the mutated allele from only one of its parents, does not show any symptoms of the disease and is clinically healthy. However, it can transmit the mutated allele to its offspring. In the case of mating two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% will inherit the mutated allele from both parents and will therefore be affected by this defect.

A genetic test can clearly reveal the genotype of the animal and is a suitable tool for breeders to prevent the unintentional reproduction of affected puppies.

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References:

Hytönen, M.K., Arumilli, M., Sarkiala, E., Nieminen, P., Lohi, H. : Canine models of human amelogenesis imperfecta: identification of novel recessive ENAM and ACP4 variants. Hum Genet 138:525-533, 2019. Pubmed reference: 30877375. DOI: 10.1007/s00439-019-01997-8