Animal models for bone and joint disease. ttw (tiptoe walking), a model mouse of OPLL (ossification of the posterior longitudinal ligament of the spine)].

Shiro Ikegawa

Laboratory for Bone and Joint Diseases, Center for Genomic Medicine, RIKEN.

Clinical calcium 2011 Feb

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ttw (tiptoe walking), a known model mouse of OPLL (ossification of the posterior longitudinal ligament of the spine) is reviewed. ttw is a natural mutant which shows generalized ectopic calcification followed by ossification in the Achiles tendon, ear and spinal ligaments, etc. The trait is caused by a homozygous nonsense mutation in the gene for NPPS (nucleotide pyrophosphatase) , a cell-membrane enzyme that produces pyrophosphate. Its pathomechanism is the decrease of extracellular pyrophosphate due to insufficiency of NPPS. ttw is a excellent model for ectopic calcification and ossification. Several interesting genes related to ectopic calicification have been identified by studies using this mouse.

Citation

Shiro Ikegawa. Animal models for bone and joint disease. ttw (tiptoe walking), a model mouse of OPLL (ossification of the posterior longitudinal ligament of the spine)]. Clinical calcium. 2011 Feb;21(2):294-300