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Y.-C. Ko, S.-J. Chen, L.-I. Lau, M.-W. Lin, C.-Y. Cheng, C. J. Liu; Variations in the Myocilin Gene in Intravitreal Triamcinolone Acetonide Injection-Induced Ocular Hypertension in a Chinese Population. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5114.
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To evaluate the association of variations in the myocilin gene (MYOC) and intraocular pressure (IOP) elevation, as well as refractory IOP elevation following intravitreal triamcinolone acetonide (IVTA) injection in a Chinese population.
Consecutive patients received a single dose of 4-mg IVTA injection and were followed for at least 6 months at our department were recruited. Eyes with a postoperative IOP elevation > 6 mmHg over baseline IOP were defined as responders. Those with elevated IOP not controlled by glaucoma medication and received further interventions were defined as refractory IOP elevation. We obtained blood samples from those who gave informed consent. The sequences of the three axons, as well as the polymorphism of promoter (-1000) of MYOC were analyzed by direct sequencing and restriction fragment length polymorphism.
Thirty-three responders, 7 with refractory IOP elevation and 50 non-responders were screened. Sixty-one instances of 8 different sequence alterations were identified: 2 changes occurred in noncoding sequences (1-83 G-A, 730+35A-G), 4 were missense mutations (Gly12Arg, Gln19His, Arg76Lys, Asp208Glu), 1 was nonsense mutation (Arg46Stop), and 1 was synonymous codon change (Thr123Thr). No sequence variation in the olfactomedin domain was identified. Three changes, Gly12Arg, Gln19His and Asp208Glu, were found in 3 responders only, and two of them had refractory IOP elevation. No sequence changes showed a significant difference between non-responders and responder, as well as those with refractory IOP elevation. The genotype of mt1 promoter did not differ between responders and non-responders.
This study identified no statistically significant evidence for a link between MYOC variation and IVTA injection related IOP elevation. However, the frequency of MYOC variation tended to be higher in responders than non-responders. Further studies are needed to clarify whether the missense mutations, Gly12Arg and Gln19His, are predictors of refractory IOP elevation following IVTA injection.
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