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Orbit. 2016 Dec;35(6):343-349. Epub 2016 Aug 31.

Constitutively low expression of collagen XIII alpha 1 may help explain the vulnerability of the inferior rectus muscle to thyroid-associated ophthalmopathy.

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a William Harvey Research Institute , University of London , London , UK.
b Department of Rheumatology and Inflammation Research , University of Gothenburg , Gothenburg , Sweden.
c Ludwig Maximilian University Eye Clinic , Munich , Germany.
d Munich University Eye Hospital , Munich , Germany.


Thyroid-associated ophthalmopathy (TAO) has a predilection for inferior rectus muscle that has never been explained. We conducted immunohistochemical staining for the soluble cleaved form of collagen XIII alpha 1 (COL13A1) and found constitutively low expression of COL13A1 in normal human inferior rectus muscles and moderate expression of COL13A1 in normal human medial rectus muscles. COL13A1 is known to be essential to development and maintenance of neuromuscular junctions and there is some evidence to suggest it may help support normal immune function. The combination of constitutively low expression of COL13A1, high physiological and metabolic demands, and consequentially relatively high exposure to stressors via the blood stream may help explain the particular vulnerability of inferior rectus to TAO compared to other extraocular muscles.


COL13A1; collagen XIII; thyroid eye disease; thyroid-associated ophthalmopathy

[Indexed for MEDLINE]

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