Health Burden of Hypophosphatasia

This is an observational retrospective study to describe the clinical problems and healthcare use of adults and children with hypophosphatasia. Interviews will be conducted with patients with childhood- and adult-onset hypophosphatasia (and the parents of the children). Hospital notes, appointment records and GP summary care records will also be reviewed. These sources will be used to describe their clinical problems, how these problems affect their daily function, and which healthcare services they have used. Patients will attend for a single visit to obtain informed consent and conduct the interview. Health problems specifically assessed in detail will include: * Fractures * Dental problems * Skeletal complications * Mobility problems * Neurosurgical complications * Seizures * Respiratory complications * Depression and anxiety * Side effects of treatment including hypercalcaemia and hyperphosphataemia Deaths will also be recorded Health care resource assessment will include * Primary care episodes * Secondary and tertiary care outpatient episodes * In-patient episodes * Nutritional support * Therapy support * Dental treatment * Over the counter medication use A case data report form will be developed as an iterative process through the period of the interviews to ensure that all data of potential interest is captured. Because the condition is not well described it is important that the data reported is not limited to the areas where it might be already expected to find problems.