ossification of the posterior longitudinal ligament of the spine
ossification of the posterior longitudinal ligament of the spineA common (up to 4% in Asians) autosomal recessive myelopathy (OMIM:602475), which can cause spinal-cord compression leading to tetraparesis.
Dagger sign is typically seen in T4-T7.
OPLL is cause by:
(1) A defect of COL6A1, which encodes collagen VI, a cell binding collagen; and
(2) Loss of function mutations in ENPP1, which encodes a transmembrane glycoprotein that regulates soft tissue calcium and bone and joint cartilage mineralisation by generating pyrophosphate (PPi), a physiological inhibitor of hydroxyapatite crystal formation and a suppressor of chondrogenesis.