Pseudoexfoliation syndrome-associated genetic variants affect transcription factor binding and alternative splicing of LOXL1

Although lysyl oxidase-like 1 ( LOXL1 ) is known as the principal genetic risk factor for pseudoexfoliation (PEX) syndrome, a major cause of glaucoma and cardiovascular complications, no functional variants have been identified to date. Here, we conduct a genome-wide association scan on 771 German PEX patients and 1,350 controls, followed by independent testing of associated variants in Italian and Japanese data sets. We focus on a 3.5-kb four-component polymorphic locus positioned spanning introns 1 and 2 of LOXL1 with enhancer-like chromatin features. We find that the rs11638944:C>G transversion exerts a cis -acting effect on the expression levels of LOXL1 , mediated by differential binding of the transcription factor RXRα (retinoid X receptor alpha) and by modulating alternative splicing of LOXL1 , eventually leading to reduced levels of LOXL1 mRNA in cells and tissues of risk allele carriers. These findings uncover a functional mechanism by which common noncoding variants influence LOXL1 expression. LOXL1 is a genetic risk factor for pseudoexfoliation syndrome of the eye but a causal variant has not been identified. Here, Pasutto et al ., find intronic LOXL1 risk variants influence transcription factor binding and alternative splicing of LOXL1 in affected tissues reducing levels of LOXL1 mRNA.