Symmetrical enchondromatosis is associated with duplication of 12p11.23 to 12p11.22 including PTHLH.

We describe a patient with striking generalized symmetrical enchondromatosis of the tubular bones and a de novo duplication of chromosome 12p11.23 to 12p11.22. The PTHLH gene within this region encodes a ligand for PTHR1: mutations in the gene encoding this receptor are associated with some cases of Ollier disease, several skeletal dysplasias including Blomstrand, Eiken, and Jansen and down-regulation of PTHLH expression in brachydactyly type E. Our findings suggest that abnormal PTHLH-PTHR1 signaling may underly this unusual form of enchondromatosis and indicate that unlike most cases of Ollier disease it is dominantly inherited.