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Shi Song Rong, Louis R Pasquale, Janey L. Wiggs; Evaluation of ATXN2 intermediate polyglutamine expansions in primary open-angle glaucoma. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3817.
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To evaluate the association of the polyglutamine (CAG) expansions in ATXN2 with primary open-angle glaucoma (POAG) and related phenotypes.
We sequenced the ATXN2 CAG expansion in 221 POAG cases using next-generation sequencing followed by validation using Sanger sequencing. To test the association with POAG, we compared the allele frequencies of ≤23 repeats (normal) with ≥27 repeats in our cases and a published Caucasian control cohort. We further assessed the link between the expansions and POAG-related phenotypes (e.g., maximum intraocular pressure [IOP] and vertical cup-disc ratio [VCDR] in either eye) using multiple linear regressions. Subgroup analyses were performed in high- (HTG) and normal-tension cases (NTG).
We found that 22 repeats of the CAG expansion was the most common allele in the POAG cases (88%) followed by the 23 repeats (7.2%) and 27 repeats (1.8%) alleles. The 27 repeats allele was significantly associated with increased risk of POAG (OR=3.27, 95%CI 1.31-8.19, P=0.011) and HTG (OR=4.54, 95%CI 1.75-11.83, P=0.0019). Moreover, we found that a larger number of CAG repeats was positively associated with IOP (Coefficient=0.45, Pregression=0.049) after adjusting for age and gender. NTG cases with ≥24 repeats had a higher IOP level (P=0.050) and a suggestively greater VCDR (P=0.069) when compared with cases with ≤23 repeats.
ATXN2 intermediate CAG repeat expansions were associated with increased risk of POAG and its related phenotypes. Replication studies and biological investigations characterizing the roles of the ATXN2 CAG expansions in glaucoma are warranted.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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