Odontohypophosphatasia

(OMIM phenotype number #146300)

Odontohypophosphatasia is a form of Hypophosphatasia (see also HPP) with primarily only dental manifestations, in the absence of skeletal system abnormalities, such as rickets or osteomalacia. About 150 cases have been reported to date. Autosomal recessive and autosomal dominant patterns of inheritance are reported in odonto-HPP. This disease may affect both children and adults, and it is caused by heterozygous mutation in the gene encoding tissue-nonspecific alkaline phosphatase (ALPL), with generalized reduction of activity of the tissue-non-specific (liver/bone/kidney) isoenzyme of ALP (TNSALP). Dental X-rays show reduced alveolar bone and enlarged pulp chambers and root canals.

Gene 

ALPL gene, 1p36.12 (OMIM gene/locus number *171760)

Phenotype

Very mild form, early-onset periodontitis, premature loss of primary and secondary teeth, the anterior deciduous teeth are more likely to be affected and the most frequently lost are the incisors, severe dental caries, decreased alveolar bone, and enlarged pulp chamber.

Main biochemical alterations

Low ALP, high PLP (pyridoxal-5’-phosphate), PEA (phosphoethanolamine).

Fig. The radiograph shows decreased mineralization of the alveolar bone and enlarged pulp chambers.

Reproduced from Eur J Pediat,  Infantile loss of teeth: odontohypophosphatasia or childhood hypophosphatasia, 2013;172:851-3, Haliloglu B, Guran T, Atay Z, et al., with permission of Springer.

Other resources

 

References

  1. Foster BL, Sheen CR, Hatch NE et al.  Periodontal Defects in the A116T Knock-in Murine Model of Odontohypophosphatasia. J Dent Res. 2015 May;94(5):706-14.
  2. Martins L, Rodrigues TL, Ribeiro MM, et al. Novel ALPL genetic alteration associated with an odontohypophosphatasia phenotype. Bone. 2013 Oct;56(2):390-7.
  3. Bianchi ML, Hypophosphatasia: an overview of the disease and its treatment. Osteoporos Int. 2015 Aug 6. [Epub ahead of print]
  4. Masi L, Agnusdei D, Bilezikian J et al. Taxonomy of rare genetic metabolic bone disorders. Osteoporos Int. 2015 Jun 13.
  5. http://www.omim.org