Only a small percentage (<30%) of individuals with TRPSI will have microdeletions of 8q that can be detected by FISH. The majority of patients with TRPSI (70%) have point mutations in the TRPSI gene. Due to the clinical variability of both Langer-Giedion syndrome (LGS) and TRPSI, patients deleted for the TRPSI locus will be offered additional testing to detect the deletion of EXT1 associated with Langer-Giedion syndrome.