Hypophosphatasia – Odontohypophosphotasia

What else is it called?

Odontohypophosphatasia is also known as: 

  • Odonto-HPP 

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What causes it?

Odonto-HPP is caused by a problem in a gene known as ALPL which also causes hypophosphatasia.  

How common is it?

The true prevalence of odonto-HPP is unknown. However, there have been 150 cases reported to date but it is speculated that odonto-HPP Is the most frequent form of HPP.  

What are the signs and symptoms?

Odonto-HPP begins to manifest during adulthood and the signs and symptoms are: 

  • Premature exfoliation of fully rooted primary teeth  
  • Short tooth roots 
  • Premature loss of primary and secondary teeth  
  • Decreased alveolar bone 
  • Expanded root chamber 

How is it diagnosed?

Odonto-HPP can be diagnosed using molecular genetic testing. It can also be diagnosed using samples of blood to look for hypercalcinaemia. 

Can it be treated?

Dental complications associated with odonto-HPP are managed with the appropriated surgery or possibly dental implantation.

Do my family need to be tested?

Different forms of hypophosphatasia can either have autosomal recessive or autosomal dominant inheritance patterns. Humans are made up of DNA and the DNA is made up of chromosomes. Genes are sections of DNA which provide instructions to produce a protein that has a specific function. When there is an issue with a particular gene it causes the protein to be made incorrectly leading to disease. Humans inherit chromosomes from both their mother and father in the forms of eggs and sperm and these chromosomes determine the child’s characteristics. An inherited autosomal recessive disease is a disease that a child will inherit from their parents. Every human has two genes needed to make a functioning TNSALP and when both of the genes are not working odonto-HPP will develop. For a child to develop odonto-HPP they will need to inherit one non-working gene from each parent. The parents do not necessarily need to be diagnosed with odonto-HPP to pass it on, they can also be carriers. a carrier is someone who possess’ one non-working gene but does not have the disease because the other gene is working correctly.  

In the event that both of the parents are carriers of odonto-HPP. There is a: 

  • 25% chance that one of the children will be unaffected by odonto-HPP will not be a carrier. 
  • 25% chance that the child will inherit odonto-HPP. 
  • 50% chance that the child will be unaffected by odonto-HPP and will be a carrier.     

In autosomal dominant inheritance patterns, we inherit particular chromosomes from the egg from the mother and sperm from the father. Every human has two genes that are needed in order to make the protein TNSALP. In an autosomal dominant disorder, a child only needs to inherit one of the non-working ALPL gene in order for the child to inherit it.  

When one parent has odonto-HPP, the chance of the baby getting odonto-HPP in each pregnancy is as follows: 

  • 50% unaffected if they receive two working genes 
  • 50% affected if they receive at least one fault gene.

Relevant Organisations

References

References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing helen@metabolicsupportuk.org [Resource Library No: AAP002]. 

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