Two novel mutations of COMP in Japanese boys with pseudoachondroplasia

Mutations in the cartilage oligomeric matrix protein (COMP) gene cause both pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED). Most mutations in COMP are located in the region encoding type 3 thrombospondin like domain (TSP3D). We report two Japanese boys with PSACH who had different novel in-frame deletions in TSP3D. The result recapitulates previous reports in that the in-frame deletions in TSP3D preferentially caused PSACH rather than MED