Although the exact cause of JIA is unclear, as children grow older, symptoms often improve, which means they can live a normal life. Langer-Giedion Syndrome is often a true contiguous gene deletion syndrome due to deletions both in the TRPS and EXT1 genes. The lack of a functional EXT1 gene causes the bone exostoses, bone anomalies and facial abnormalities which can be noticed in patients. The EXT1 gene and the TRPS1 gene tend to be absent in patients and research suggests that other genes based in the 8q24.11-8q24.13 region of chromosome 8 may be deleted or non-functional also. Longer deletions in this area are characterized by mental retardation and also the other variations in symptoms stated previously.