The COHIR Study - a Non-interventional, Prospective, Single-center Investigation With Exploratory Data Analysis to Assess the Proportion of Patients With Hypophosphatasia Presenting at the Department of Rheumatology and Establishment of an Algorithm to HPP Diagnosis.

Hypophosphatasia (HPP) is a rare genetic disorder (1-3/300,000 severe cases in Europe) caused by one or more mutations in the alkaline phosphatase (ALP) gene. Hypomineralization results in symptoms such as arthralgias, insufficiency fractures, and poor dental status beginning in childhood. A fatal outcome is conceivable in circumstances of early infancy first presentation. In consistency with the musculoskeletal complaint pattern, HPP is far more common in the rheumatology patient population than in the general population.

However, HPP is still frequently misdiagnosed as some other form of bone disease (e.g., rickets, osteomalacia, or osteoporosis). Therefore, implementation of a clinically applicable algorithm for early hypophosphatasia detection is needed.

The primary aim of this prospective observational study is to determine the prevalence of hypophosphatasia in adult patients in rheumatology. Moreover, a further goal is to establish an algorithm that reliably separates adult HPP patients from other, rheumatologic and bone diseases.