A global consortium of researchers, anchored by the University of Manchester, has produced the most granular map to date detailing how genetic variations shape the functionality of the human eye.
This advancement holds the potential to illuminate the reasons behind the development of vision-threatening conditions like age-related macular degeneration (AMD) in millions, as well as less common inherited eye disorders. The findings of this study have been published in the journal Nature Communications.
Epidemiological projections indicate that age-related macular degeneration (AMD), a primary driver of vision impairment in adults, is anticipated to affect 288 million individuals worldwide by the year 2040.
Among the more infrequent inherited eye diseases that disrupt the function of retinal cells responsible for light detection and transmission of visual signals to the brain are Stargardt disease, retinitis pigmentosa, and cone-rod dystrophy.
The research team conducted an in-depth analysis of whole-genome sequencing data, complemented by RNA profiles derived from 201 donated human eyes. This enabled them to scrutinize two critical ocular tissues involved in vision: the neurosensory retina, which captures light, and the retinal pigment epithelium, which provides essential support and nourishment.
By correlating genetic differences with gene activity within these tissues, the scientists identified over 1.4 million genetic signals that influence the activation or deactivation of genes, termed expression quantitative trait loci, or eQTLs.
These signals exert an influence on the behavior of nearly 10,000 genes within the retina and approximately 4,000 genes in the retinal pigment epithelium. A significant proportion of these genetic effects were pinpointed in genomic regions that function as regulatory switches, orchestrating gene expression.
The investigation also flagged hundreds of individuals exhibiting unusually high or low retinal gene activity compared to typical levels. Among these ‘expression outliers,’ the researchers discovered close to 300 rare genetic variants that could plausibly account for the atypical gene activity.
These variants encompassed rare alterations in non-coding DNA regions, as well as more substantial structural rearrangements and variations in the number of copies of specific DNA segments within individuals.
“Our study represents a crucial stride towards deciphering the intricate genetic architecture of the human eye,” state the researchers.
Collectively, these account for approximately 28% of outliers, paving the way for enhanced understanding of how rare mutations contribute to the pathogenesis of eye diseases.
The published results offer an unprecedented resource for scientists investigating the genetic underpinnings of visual impairments, and this dataset will be accessible to the broader research community. Furthermore, they lay the groundwork for future endeavors in personalized therapies and early diagnostic approaches.
“Our study marks a significant step in unraveling the complex genetic blueprint of the human eye,” commented co-lead author Jamie Ellingford from the University of Manchester. “And it opens avenues for novel strategies to protect and restore vision in the future. It demonstrates how both common and rare genetic variations influence their manifestation in the human retina. Understanding these patterns brings us closer to elucidating the biological mechanisms behind inherited vision loss and developing more targeted treatments.”
“We are hopeful that this dataset will catalyze discoveries in ophthalmology, genetics, and personalized medicine,” added co-lead author Jacob Sami of the University of Manchester. “And we anticipate it will aid in identifying individuals at risk for vision-threatening diseases even before symptoms emerge.”
“Such fundamental discoveries are only achievable through the utilization of highly characterized human donor material,” noted Professor Simon J. Hoerner from the University of Tübingen, Germany. “We are exceptionally fortunate to have access to one of Europe’s largest repositories of human eyes, established in Manchester in 2015. We remain eternally grateful for the extraordinary generosity of all the donors and their families who have contributed over the years.”
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