Exfoliation syndrome (XFS) is the commonest known risk factor for secondary glaucoma and a significant cause of blindness worldwide. Variants in two genes, LOXL1 and CACNA1A have been previously associated with XFS. To further elucidate the genetic basis of XFS, we collected a global sample of XFS cases to refine the association at LOXL1, which previously showed inconsistent results between populations, and to identify new variants associated with XFS. We identified a rare, protective allele at LOXL1 (p.407Phe, OR = 25, P =2.9 × 10−14) through deep resequencing of XFS cases and controls from 9 countries. This variant results in increased cellular adhesion strength compared to the wild-type (p.407Tyr) allele. A genome-wide association study (GWAS) of XFS cases and controls from 24 countries followed by replication in 18 countries identified seven genome-wide significant loci (P < 5 × 10−8). Index variants at the new loci map to chromosomes 13q12 (POMP), 11q23.3 (TMEM136), 6p21 (AGPAT1), 3p24 (RBMS3) and 5q23 (near SEMA6A). These findings provide biological insights into the pathology of XFS, and highlight a potential role for naturally occurring rare LOXL1 variants in disease biology.

The high prevalence of glaucoma (7.3%) in the Akinyele district in southwestern Nigeria is comparable with those in predominantly black populations in the Akwapim-South district of Ghana and Barbados. Primary open angle glaucoma remains the most prevalent form of glaucoma.

Purpose:The purpose of this study was to estimate the prevalence of exfoliation syndrome (XFS) and its association with ocular disease in patients attending the eye clinic of the University College Hospital (UCH) in Ibadan, Nigeria.Materials and Methods:A total of 448 consecutive new patients, aged 30-90 years who presented to the eye clinic of UCH between December 2009 and November 2010 were evaluated. Each patient had a complete ophthalmic examination. Patients with exfoliative material on the anterior lens surface and/or pupillary margin in either or both eyes were considered to have XFS. Means, standard deviation, and 95% confidence intervals were calculated.Results:All the patients examined were from the southern part of Nigeria. Majority (94.2%) were of the Yoruba tribe from southwestern Nigeria, while 5.8% were from southeastern Nigeria. The mean age of the study cohort was 58.5 ± 13.8, 54.8% were males, 12 (2.7%) had XFS. All patients with XFS were of the Yoruba tribe, with a mean age 65.6 ± 5.6 years. There was a male predilection (66.7%). All eyes with XFS had lenticular opacities. XFS was bilateral in eight patients (66.7%) of whom seven patients (87.5%) had glaucoma and lenticular opacities bilaterally.Conclusion:This is the first report of the existence of XFS in Nigeria. Larger studies are necessary in this population to further investigate the disease.

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