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

Abstract

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 in Baja Verapaz Guatemala: A Cross-Sectional Study and Review of the Literature

“…Reported prevalence of XFS varies significantly across populations, with 0% in Eskimos [ 31 ], 0.8% in Kathmandu (Nepal) [ 39 ], 1.8% USA [ 40 ], 6.45% in Pakistan [ 41 ], 7.4% in India [ 42 ], 9.6% in Iran [ 43 ], 5–25% in Scandinavian countries [ 31 ], and 0.6% [ 44 ] and 38% in Navajo Indians [ 45 ]. Minimal XFS data exist in Latin American populations besides a single case in Brazil [ 46 ], a prevalence of 14.5% in Argentina [ 47 ], 15% in a western Guatemalan cataract population [ 36 ], and 24% in a Mayan cohort (22% had XFS and cataracts) [ 38 ]. Our specific Guatemalan population presenting to outreach eye camps to assess their vision and for possible surgical intervention appears to have a high prevalence of XFS/XFG of 36%.…”

“…This cross-sectional observational study demonstrates that the prevalence of XFS/XFG in Guatemalans in the Baja Verapaz region seeking eye care and interventions during a Moran Outreach trip was upwards of 36%. This rate is on the upper end compared to other populations globally and elevated compared to 15% in a western Guatemalan cataract population [ 36 ] and 24% in a Mayan cohort (22% also had cataracts) [ 38 ]. Larger epidemiology studies are warranted to better understand the prevalence and impact of XFS/XFG.…”

“…Other XFS prevalence rates include 0.4% in China [ 32 ], 13% in Spain [ 33 ], 7.8–12% for Gurung and 0.3% for Tamang peoples in Nepal [ 34 ], and 2.4% in women over the age of 65 in our Utah population [ 35 ]. One study found an XFS prevalence of 15% in western Guatemala and another found 24% in Baja Verapaz (22% had XFS and cataracts), but there are little epidemiologic data on XFS and XFG prevalence or incidence in Guatemala, especially in the Baja Verapaz region [ 36 , 37 , 38 ]. This observational study assessing XFS, XFG, and possible demographic factors of this region aims to better understand unique exogenous and endogenous risk factors that may be associated with XFS in Guatemalans.…”

Factors associated with the presence of cataracts in the Peruvian population older than 50 years: a cross-sectional study

“…In this regard, a previous study in a geographically isolated Guatemalan native population reported a high prevalence of cataracts (54.8%). 39 It has been reported that the native population (including Quechua, Aimara, and native or indigenous ethnic groups of the Amazon), which is part of ethnic minorities, tends to experience limitations in access to health services, including ophthalmologic care, with a lack of effective strategies to achieve better communication and distribution of medical care among the native population. 39 In Peru, there are barriers such as the shortage of ophthalmologists, surgeons, and equipment for the definitive treatment of cataracts, thereby generating great inequity mainly affecting socially and economically disadvantaged populations such as the native population.…”

Efficacy of Selective Laser Trabeculoplasty after iStent Implantation in Primary Open-Angle Glaucoma

“…Though our sample size was limited, it included a diverse population, including racial and ethnic minorities. Even with a small sample size, it is important to include populations that may go understudied within research because, if such populations are ignored, health disparities will only further increase [ 41 ]. An additional limitation was observing the data retrospectively in electronic medical record history, which could cause additional bias.…”