Pseudoexfoliation and Cataract Syndrome Associated with Genetic and Epidemiological Factors in a Mayan Cohort of Guatemala.

The Mayan population of Guatemala is understudied within eye and vision research. Studying an observational homogenous, geographically isolated population of individuals seeking eye care may identify unique clinical, demographic, environmental and genetic risk factors for blinding eye disease that can inform targeted and effective screening strategies to achieve better and improved health care distribution. This study served to: (a) identify the ocular health needs within this population; and (b) identify any possible modifiable risk factors contributing to disease pathophysiology within this population. We conducted a cross-sectional study with 126 participants. Each participant completed a comprehensive eye examination, provided a blood sample for genetic analysis, and received a structured core baseline interview for a standardized epidemiological questionnaire at the Salama Lions Club Eye Hospital in Salama, Guatemala. Interpreters were available for translation to the patients' native dialect, to assist participants during their visit. We performed a genome-wide association study for ocular disease association on the blood samples using Illumina's HumanOmni2.5-8 chip to examine single nucleotide polymorphism SNPs in this population. After implementing quality control measures, we performed adjusted logistic regression analysis to determine which genetic and epidemiological factors were associated with eye disease. We found that the most prevalent eye conditions were cataracts (54.8%) followed by pseudoexfoliation syndrome (PXF) (24.6%). The population with both conditions was 22.2%. In our epidemiological analysis, we found that eye disease was significantly associated with advanced age. Cataracts were significantly more common among those living in the 10 districts with the least resources. Furthermore, having cataracts was associated with a greater likelihood of PXF after adjusting for both age and sex. In our genetic analysis, the SNP most nominally significantly associated with PXF lay within the gene KSR2 (p < 1 × 10-5). Several SNPs were associated with cataracts at genome-wide significance after adjusting for covariates (p < 5 × 10-8). About seventy five percent of the 33 cataract-associated SNPs lie within 13 genes, with the majority of genes having only one significant SNP (5 × 10-8). Using bioinformatic tools including PhenGenI, the Ensembl genome browser and literature review, these SNPs and genes have not previously been associated with PXF or cataracts, separately or in combination. This study can aid in understanding the prevalence of eye conditions in this population to better help inform public health planning and the delivery of quality, accessible, and relevant health and preventative care within Salama, Guatemala.

Exfoliation syndrome associated with LOXL1 gene polymorphisms in a Black patient from Latin America: a case report / Síndrome de esfoliação associada a polimorfismos do gene LOXL1 em paciente negro da América Latina: relato de caso

ABSTRACT A 89-year-old Black female with a 6-year history of advanced open-angle glaucoma was referred to the Glaucoma Service of the Ophthalmology Department - Federal University of São Paulo (UNIFESP). Best-corrected visual acuity was 20/400 in the right eye and 20/60 in the left eye. Pseudoexfoliation material was observed at the iris border, angle, and the anterior lens surface. Anterior biomicroscopy revealed exfoliation material forming an evident peripheral zone and a central disc separated by a clear intermediate zone on the anterior lens surface OU. Gonioscopy showed an open-angle Sampaolesis's line and whitish material deposits OU. Fundus examination revealed a cup-to-disc ratio of 1.0 OU with peripapillary atrophy. Genetic analysis for single nucleo­tide polymorphisms of the lysyl oxidase-like 1 gene linked to exfoliation syndrome identified two such single nucleotide polymorphisms, rs1048661 and rs216524.

RESUMO Uma mulher negra de 89 anos com um histórico de seis anos de glaucoma avançado de ângulo aberto avançado foi encaminhada ao Serviço de Glaucoma do Departamento de Oftalmologia da Universidade Federal de São Paulo (UNIFESP). A acuidade visual melhor corrigida era 20/400 no olho direito e 20/60 no olho esquerdo. Material pseudo-exfoliativo foi observado na borda iriana, ângulo e superfície anterior do cristalino. A biomicroscopia de segmento anterior demonstrou material exfoliativo formando uma zona periférica evidente e um disco central separado por uma zona intermediária livre na cápsula anterior do cristalino. A gonioscopia mostrou uma linha de Sampaolesi de ângulo aberto e depósitos esbranquiçados. O exame de fundo de olho revelou disco óptico com escavação total em ambos os olhos com atrofia peripapilar. A análise genética para polimorfismos de nucleotídeo único do gene semelhante à lysyl oxidase-like 1 ligado à síndrome de esfoliação identificou dois desses polimorfismos de nucleotídeo único, rs1048661 e rs216524.

Exfoliation syndrome associated with LOXL1 gene polymorphisms in a Black patient from Latin America: a case report.

A 89-year-old Black female with a 6-year history of advanced open-angle glaucoma was referred to the Glaucoma Service of the Ophthalmology Department - Federal University of São Paulo (UNIFESP). Best-corrected visual acuity was 20/400 in the right eye and 20/60 in the left eye. Pseudoexfoliation material was observed at the iris border, angle, and the anterior lens surface. Anterior biomicroscopy revealed exfoliation material forming an evident peripheral zone and a central disc separated by a clear intermediate zone on the anterior lens surface OU. Gonioscopy showed an open-angle Sampaolesis's line and whitish material deposits OU. Fundus examination revealed a cup-to-disc ratio of 1.0 OU with peripapillary atrophy. Genetic analysis for single nucleo-tide polymorphisms of the lysyl oxidase-like 1 gene linked to exfoliation syndrome identified two such single nucleotide polymorphisms, rs1048661 and rs216524.

The T allele of lysyl oxidase-like 1 rs41435250 is a novel risk factor for pseudoexfoliation syndrome and pseudoexfoliation glaucoma independently and through intragenic epistatic interaction.

PURPOSE: Two coding single nucleotide polymorphisms (SNPs) in lysyl oxidase-like 1 (LOXL1) are major genetic risk factors for pseudoexfoliation syndrome (XFS) and pseudoexfoliation glaucoma (XFG) in diverse populations. However, recent conflicting results suggest that the currently known disease-associated missense variants R141L and G153D are not causal and that they may be proxies for other unknown functional LOXL1 variants. The purpose of this study was to investigate the possible association of XFS/XFG with a novel LOXL1 exonic variant. METHODS: Genotypes of the synonymous coding LOXL1 SNP rs41435250 (p.A310A) were identified with direct sequencing. A case-control study was conducted with 115 unrelated Mexican patients with XFS/XFG (43 XFS/72 XFG) as well as 130 control subjects. Allele frequencies, genotype frequencies, and Hardy-Weinberg equilibrium were assessed with the HaploView software. A probable intragenic epistasis effect was assessed by comparing the frequencies of the rs41435250 alleles among a subset of 51 patients with XFS/XFG without the high-risk TT genotype at LOXL1 intronic rs2165241 and the control group. RESULTS: The T allele of the exonic SNP rs41435250 was more frequent in patients with XFS/XFG than in controls (odds ratios [95% confidence intervals] = 2.0 [1.1-3.6]; p = 0.01). Interestingly, the strength of association with the rs41435250 T allele was strongly increased (odds ratio [95% confidence intervals] = 4.9 [2.7-9.1]; p = 0.00000005) in the subgroup of subjects without the risk genotype at rs2165241. CONCLUSIONS: Our results indicate that allele T of rs41435250 is a novel risk genetic factor for XFS/XFG development in our population and points toward the possibility of a LOXL1 intragenic epistatic effect between rs41435250 and rs2165241. Functional studies are needed to investigate if the synonymous p.A310A mutation could affect messenger ribonucleic acid stability and thus LOXL1 enzymatic activity.

Prevalence of high-risk alleles in the LOXL1 gene and its association with pseudoexfoliation syndrome and exfoliation glaucoma in a Latin American population.

PURPOSE: Pseudoexfoliation syndrome (XFS) is a major risk factor for exfoliation glaucoma (XFG). A significant association exists between XFG and several SNPs in the lysyl oxidase-like 1 (LOXL1) gene. The purpose of this study was to report the results of the first association study between LOXL1 polymorphisms and XFS and/or XFG in a Latin American population. METHODS: Genotypes of three high-risk SNPs of LOXL1 (rs1048661, rs3825942, and rs2165241) were analyzed by direct sequencing. A case-control study was conducted with 102 unrelated XFS/XFG Mexican patients (42 XFS/60 XFG) as well as 97 control subjects. Allele frequencies, Hardy-Weinberg equilibrium, and haplotype association analysis were assessed with the Haplo View software. RESULTS: The T allele of the intronic SNP rs2165241 was more frequent in XFS/XFG patients than in controls (OR [95% CI] = 2.41 [1.59-3.64]; p = 0.00001). The G allele of rs3825942 was found in a higher frequency in XFS/XFG than in controls (100% vs 95% respectively, p = 0.0019). No significant association between XFS and the rs1048661 (R141L) SNP was observed. The TGT haplotype was observed in a higher frequency in patients than in controls (p = 0.025), and produced the highest risk in our study (OR [95% CI] = 3.20 [1.09-9.39]; p = 0.025). CONCLUSIONS: This is the first study associating LOXL1 gene polymorphism and XFS/XFG in Latin America. LOXL1 variants are associated with an elevated risk for XFS/XFG in the Mexican population. A higher risk was conferred by the T allele of the intronic rs2165241 SNP rather than by the worldwide "high-risk" G allele of rs3825942.