Urinary Biomarkers of OI Pathobiology

Osteogenesis Imperfecta (OI) is a rare disorder that causes bones to break easily. People with OI may have broken bones with little or no trauma, dentinogenesis imperfecta (DI), and, in adult years, hearing loss. It is seen in both genders and all races. OI can range from very severe to very mild. Individuals with the most severe type of OI may die at birth. People with severe OI who survive may have bowed arms and legs, very short stature and be unable to walk. People with the mildest form of OI may only break bones occasionally and have normal height and lifespan. Breaks can occur in any bone, but are most common in the arms and legs. People with OI also often have problems with the spine. The spine problems include compression fractures and scoliosis (a curvature of the spine). DI is characterized by grey or brown teeth that may chip and wear down and break easily. In addition to weak teeth, the teeth in the upper jaw may not match up with the teeth in the lower jaw.

Before the genetic cause of OI was known, OI was classified into four types. Each type was based upon the symptoms and severity of OI. In most people with OI, the cause is a change in one of the genes that makes a protein called type 1 collagen. In the past decade, it was discovered that in about 5% of people with OI it is in another gene. Some doctors now classify OI both on how severe it is as well as which gene is causing OI. When people classify OI this way, there are more than 10 types of OI. The current laboratory testing to determine OI subtype involves the collection of blood and/or skin cells.