Test Detail

Dental hypomineralisation of the Border Collie is a hereditary disorder of dental development, the canine model of human Raine syndrome. It produces enamel and dentine deficient in mineralisation, with severe dental wear, pulp exposure, pulpitis and the need for extractions. It affects both deciduous and permanent dentition. In the dog, the progressive skeletal dysplasia that characterises human Raine syndrome has not been described.

Border Collie: carrier frequency of 11% in the sampled population. No carriers were detected in 186 dogs of 20 other breeds, supporting that the variant is breed-specific.

- Severe dental wear (attrition not explained by abnormal contact or abrasive chewing)\n- Thin, matte enamel with brown discolouration; dentine with abnormal globular areas\n- Pulp exposure and pulpitis with pain\n- Loss of crown and need for extraction of multiple teeth\n- Involvement of deciduous and permanent dentition\n- Skeletal involvement has not been documented in the dog

A Border Collie breeder contacted researchers about a family with several dogs affected by severe dental wear with pulpitis and extractions; clinical, radiological and histological examination confirmed dental hypomineralisation with an autosomal recessive inheritance pattern. Whole-genome sequencing of several affected dogs, filtered against obligate carriers and controls, identified a homozygous missense variant in FAM20C (c.899C>T, p.A300V), at a highly conserved residue of the kinase domain. The variant segregated completely with the phenotype and showed a carrier frequency of 11% in the breed. FAM20C defects cause Raine/FGF23 syndrome in humans, which establishes the dog as a model of the human disease.

- Test Border Collie breeding animals before the first mating\n- Homozygotes (R/R) should NOT be bred\n- Carriers (R/N) should only be crossed with N/N\n- A carrier may be crossed with a clear animal; offspring intended for breeding must be tested\n- Keep genetic records in the pedigree\n- Regular dental check-ups: dental examination under anaesthesia allows early wear to be detected

The differential diagnosis includes other enamel hypoplasias/hypomineralisations (for example, amelogenesis imperfecta due to ENAM in the Italian Greyhound), dentine dysplasia and defects due to fever or tetracyclines. Histology shows globular dentine and interglobular spaces, with thin enamel. There is no treatment for hypomineralisation; management focuses on preventive dental care and extraction of severely damaged teeth. Unlike human Raine syndrome, skeletal dysplasia has not been described in the dog.

1. Hytönen MK, Arumilli M, Lappalainen AK, et al. Molecular Characterization of Three Canine Models of Human Rare Bone Diseases: Caffey, van den Ende-Gupta, and Raine Syndromes. PLoS Genet. 2016;12(5):e1006037. PMID: 27187611
2. OMIA:002015-9615. Dental hypomineralization in Canis lupus familiaris (dog). https://omia.org/OMIA002015/9615/