PhD student: Julia Herrou

Title: Update on the epidemiological data of rare constitutional bone disease and metabolic bone disease, in particular X-linked hypophosphatemia in adults.

Supervisor: Karine Briot

Doctoral schoolED 393 : Ecole Doctorale Pierre Louis de Santé Publique

Thesis abstract:

This thesis focuses on the epidemiology of rare calcium and phosphate diseases in France, in particular X-linked hypophosphatemia (XLH), the leading cause of genetic hypophosphatemic rickets. In France, the rare disease plans has improved the care for rare disease. The main aims were to improve access to care, knowledge of rare diseases and the care pathway.  Using data from the Banque Nationale Données Maladies Rares (BNDMR), we estimated the incidence of XLH at 2.1 per 100,000 births and a prevalence of XLH of 1.07 per 100,000 people (IC95% [0.99 – 1.15]). These results are similar to those reported in the literature. We focused a large part of our research on the epidemiology of enthesopathies and the factors associated with their development in XLH patients. We retrospectively included 114 patients with whole-body radiography (EOS®) followed up at the reference centre for rare calcium and phosphorus diseases. The prevalence of enthesopathies was 67%. Factors associated with the presence of enthesopathies were age and dental involvement. In a second study, a subgroup of patients who had 2 radiographs was used to assess structural progression. Age was the factor associated with the development of enthesopathy. Finally, we looked at the care pathway of XLH patients using data from the Entrepôt de Données de Santé (data from the Assistance Publique des Hôpitaux de Paris). The centres of reference provide multidisciplinary care.  These results need to be confirmed across the country.

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