Dysspondyloenchondromatosis (DSC) is a rare form of generalized enchondromatosis and characterized by short stature with unequal limb length, multiple enchondromas in metaphyseal and diaphyseal parts of the long tubular bones, and progressive kyphoscoliosis. Although the COL2A1 gene mutation was found to be responsible for DSC, a case of DSC with no pathogenic mutation in the COL2A1 gene has also been reported, suggesting that the condition is genetically heterogeneous. Here, we report 2 novel heterozygous mutations in COL2A1 in 2 patients with DSC. They had prenatal onset short stature with unequal limb length and generalized enchondroma-like lesions in metaphyseal and diaphyseal parts of the long tubular bones, and osteopenia. The first patient was diagnosed at 3 months of age and followed for 10.5 years. Severe lumbosacral scoliosis and recurrent fractures were observed. The second patient was diagnosed at the age of 4 years. Mild deterioration in scoliosis was observed during the 3-year-long follow-up period. However, skeletal radiography of both patients showed the improvement of enchondromatous lesions. In conclusion, we verified that the COL2A1 gene mutations are responsible for the DSC phenotype. We observed severe osteopenia and fractures which were not reported previously.

Dysspondyloenchondromatosis (DSC) is a rare skeletal dysplasia characterized by enchondroma-like lesions and anisospondyly. The former leads to discrepancies in limb length, and the latter, to progressive kyphoscoliosis. Two recent cases have highlighted the genetic heterogeneity of DSC, one demonstrating the presence and, the other, the absence of a COL2A1 mutation. This may have important clinical implications, for example, screening for complications including atlanto-axial instability associated with type II collagenopathies, as well as long-term patient management. We report on a case with radiographic features of DSC with overlap into the type II collagenopathy spondyloepimetaphyseal dysplasia, Strudwick type, who was found to carry a novel heterozygous mutation in the COL2A1 gene. Testing for COL2A1 mutations should be performed in all patients with radiological features of DSC. Further research is needed to identify the underlying molecular cause in cases where no COL2A1 mutation is identified.