Health Burden of Hypophosphatasia

Hypophosphatasia (HPP) is a genetic disorder caused by mutation in the tissue-non-specific alkaline phosphatase gene (TNSALP). It causes impaired bone mineralisation, fractures, tooth loss, muscle weakness and possibly other adverse health outcomes.

The infantile-onset forms are severe, and were often fatal until the recent availability of a treatment (Asfotase Alfa). The childhood-onset forms are less severe, and the adult-onset form is mild, and often unrecognised or misdiagnosed as osteoporosis.

The less severe forms of the disease are not well described, and because there has been no available treatment there has not been much research in adults. However, now that treatment is available there is a possibility of a clinical trial in adults. To know whether there is a need for a trial there is a need to determine if there is a significant personal and economic burden associated with the less severe forms of HPP.

The study consists of a clinical interview and notes review of adults and children with confirmed (by biochemical and genetic testing) HPP attending metabolic bone clinics in Sheffield to establish their clinical problems and healthcare use. There are currently about 26 adults and 8 children attending clinics in Sheffield.

The information will be used to plan a data search and health economic analysis of the burden of HPP from the UK Clinical Practice Research Database in collaboration with Pharmatelligence (a healthcare data group based within the University of Cardiff).