Hypophosphatasy

Described for the first time in 1948, the hypophosphatasy is a Ostéopathie of origin Génétique involving an osseous demineralization of which there exist several forms: a lethal form in utero , a form of the newborn, a form of childhood and adolescence and the shape of adult. There exists finally a form known as " odontologique" characterized by a premature fall of the teeth without associated osseous signs.

This orphan Maladie touches less than one person out of 100.000. There does not exist any treatment for the time being. The patients suffer from osseous brittleness and are particularly exposed with the falls, even with spontaneous fractures. They often lose their teeth (falls premature of the baby teeth in the young child, falls of the final teeth in the adult). The most severe form involves the death of the child to the birth or little time afterwards.

The hypophosphatasy is due to changes in the gene ALPL (Alkaline Phosphatase Liver standard) which codes an enzyme, alkaline phosphatase fabric-nonspécifique (TNSALP for Tissue Nonspecific Alkaline Phosphatase). This enzyme has a crucial role in osseous mineralization, in particular by déphosphorylant inorganic pyrophosphate (PPi) out of inorganic phosphate (Pi) which is, with calcium, the main component of the osseous matrix. The changes in gene ALPL deteriorate the function of the TNSALP. It results from it a reduction from pi and an increase in PPi which is a powerful inhibiter of osseous mineralization. These changes cause a more or less serious deterioration according to their nature and their localization in the molecule, which explains the large clinical variety observed in this disease.

The mode of transmission of the hypophosphatasy is Récessif autosomic in the severe forms (forms antenatal and infantile) but it can be recessive or Dominating autosomic in the moderate forms (forms youthful, adult and odontological). Consequently, the risk for a couple having already had a child reached of a severe form of hypophosphatasy to have another child reached is of 1/4. In the not very severe forms, this risk can be 1/4 (recessive transmission) or 1/2 (dominant transmission).

There does not exist currently any treatment of the hypophosphatasy.

Associations

Hypophosphatasie Europe, founded with Huningue by Steve Ursprung, even reached to him by the disease, gathers sick and enquiring: contact@hypophosphatasie.com

Sources

Site of a laboratory which develops research on the hypophosphatasy.

References

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