ITPR3

What is CMT1J?


  • A mutation of the ITPR3 gene results in CMT1J.
  • CMT1J is a genetic disease with an autosomal dominant inheritance pattern, meaning there is a 50% chance of each child inheriting the disease from an affected parent.
  • Muscle weakness, or atrophy, starts distally and works proximally. This means the foot muscles are affected first with weakness progressing up the legs. Some sensory impairment may also occur. CMT1J patients have difficulty walking and balancing. 
  • Age of onset is variable.
  • The disease is progressive and symptoms are highly variable from patient to patient and from parent to child.
  • Some CMT1J patients have hand muscle atrophy progressing up the arms and respiratory muscle weakness.


ITPR3 -- why is it a big deal?

  • It affects calcium function in cells, which is vital for many cell functions.
  • It has been linked to many different diseases, including cancer (lung, bone, breast to name a few)
  • ITPR3 mutations cause CMT1J, which sometimes causes severe disability or even death.


Publications

ITPR3 - general info

  Mangla A, Guerra MT, Nathanson MH. Type 3 inositol 1,4,5-trisphosphate receptor: A calcium channel for all seasons. Cell Calcium. 2020 Jan;85:102132. doi: 10.1016/j.ceca.2019.102132. Epub 2019 Nov 25. PMID: 31790953; PMCID: PMC6917836.


ITPR3 and CMT

In 2014, it was identified as a candidate gene for neuropathy:

Schabhüttl M, Wieland T, Senderek J, Baets J, Timmerman V, De Jonghe P, Reilly MM, Stieglbauer K, Laich E, Windhager R, Erwa W, Trajanoski S, Strom TM, Auer-Grumbach M. Whole-exome sequencing in patients with inherited neuropathies: outcome and challenges. J Neurol. 2014 May;261(5):970-82. doi: 10.1007/s00415-014-7289-8. Epub 2014 Mar 15. PMID: 24627108.


2020 -- paper reports family with CMT from an ITPR3 mutation

Rönkkö J, Molchanova S, Revah-Politi A, Pereira EM, Auranen M, Toppila J, Kvist J, Ludwig A, Neumann J, Bultynck G, Humblet-Baron S, Liston A, Paetau A, Rivera C, Harms MB, Tyynismaa H, Ylikallio E. Dominant mutations in ITPR3 cause Charcot-Marie-Tooth disease. Ann Clin Transl Neurol. 2020 Oct;7(10):1962-1972. doi: 10.1002/acn3.51190. Epub 2020 Sep 19. PMID: 32949214; PMCID: PMC7545616.


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