According to the variety and severity of their symptoms, patients are classified into 21 different phenotypes [2] such as Stickler syndrome type I (STL1, MIM#108300) and Spondyloepiphyseal dysplasia congenita (SEDC, MIM#183900), though clinical presentations of these phenotypes overlap considerably. This evidence concerns the gene COL2A1 and spondyloepiphyseal dysplasia congenita.