How multiple genes impact vision development and result in rare sight
disorder

Date:
April 6, 2022
Source:
University of Leicester
Summary:
An international team of health researchers have described how
genetic defects influence the spectrum of vision development and
cause problems in developing babies' eyes.



FULL STORY ==========================================================================
An international team of health researchers have, for the first time,
described how genetic defects influence the spectrum of vision development
and cause problems in developing babies' eyes.


========================================================================== Researchers from the University of Leicester led an international effort consisting of 20 expert centres in the largest study of its kind to date, examining the genes associated with arrested development of the fovea.

The fovea is part of the retina at the back of the human eye, and is the structure responsible for sharp, central vision. Arrested development
of the fovea, or foveal hypoplasia, is rare, and is often caused by
genetic changes.

This lifelong condition can have serious consequences and can affect
the individual's ability to read, drive and complete other daily tasks.

There are currently no treatments available for this condition. Most
often, during infancy, one of the first visible signs of a foveal
problem is 'wobbly eyes'. This is often seen in the first six months of
life. There are large gaps in our knowledge about which genes control
the development of the fovea and at what time points during development
this occurs.

Now, in a study published in the journal Ophthalmology combining data
from more than 900 cases across the world, researchers have been able
to identify the spectrum of genetic changes behind these foveal defects
and -- crucially -- at which point they occur in the development of the
unborn baby.

Dr Helen Kuht is a research orthoptist and Wellcome Trust post-doctoral
fellow within the Ulverscroft Eye Unit at the University of Leicester,
and first author for the study. She said: "This research has really
helped to solve the puzzle of why some babies with these genetic changes present with varying severity of foveal hypoplasia. Thus allowing us
to diagnose, predict future vision and help prioritise genetic testing, subsequent counselling, and support."


==========================================================================
Dr Mervyn Thomas is an NIHR Academic Clinical Lecturer in Ophthalmology
and Genomic Medicine at the University of Leicester and University
Hospitals of Leicester NHS Trust. He has previously pioneered a worldwide standard for grading the severity of foveal hypoplasia called the
Leicester Grading System.

Dr Thomas, lead author for this study, added: "Most previous studies in
this area have been limited to one or two centres making it difficult to
draw meaningful conclusions in rare disorders like foveal hypoplasia. With
this study we were able to combine datasets from large collaborative
centres across the globe.

"We are extremely grateful to all our collaborators that have come
forward to support this effort and the funders within each country
that has made this possible. This has helped understand how these genes influence foveal development and to what extent the foveal development is arrested based on the genetic defect." Arrested development of the fovea
is detected using a special camera, called optical coherence tomography
(OCT), that can scan the back of the eye.

Researchers used OCT scans to identify the location of the fovea,
a small pit measuring approximately 2mm in diameter.

These scans were then analysed to categorise the severity of each
individual case using the Leicester Grading System and compared with
genetic markers to identify the genes associated with varying severities
of the condition.



========================================================================== Identifying these relationships between genetic defects and the degree
of arrested foveal development is the first step in building possible
future treatments for individuals with foveal hypoplasia.

Leicester established the Foveal Development Investigators Group (FDIG)
in 2020, bringing together expertise in foveal developmental research
spanning 11 countries. These include centres in the UK, South Korea,
Denmark, Netherlands, USA, China, France, Australia, Germany, Brazil
and India.

Dr Brian Brooks is a Senior Investigator at the National Eye Institute
in the USA, branch chief for ophthalmic genetics and visual function, and co-author for this study. He added: "Dr Kuht and Dr Thomas have assembled
the world's largest consortium of investigators interested in causes of
foveal hypoplasia. Their work represents the best cross-sectional data we
have on the genetics of this condition to date." The study was funded
by the UK Medical Research Council, Fight for Sight, Nystagmus Network, Ulverscroft Foundation, Wellcome Trust, Korea Centers for Diseases
Control and Prevention, the National Research Foundation of Korea.


========================================================================== Story Source: Materials provided by University_of_Leicester. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Helen J. Kuht, Gail D.E. Maconachie, Jinu Han, Line Kessel, Maria
M. van
Genderen, Rebecca J. McLean, Michael Hisaund, Zhanhan Tu, Richard W.

Hertle, Karen Gronskov, Dayong Bai, Aihua Wei, Wei Li, Yonghong
Jiao, Vasily Smirnov, Jae-Hwan Choi, Martin D. Tobin, Viral Sheth,
Ravi Purohit, Basu Dawar, Ayesha Girach, Sasha Strul, Laura May,
Fred K. Chen, Rachael C. Heath Jeffery, Abdullah Aamir, Ronaldo
Sano, Jing Jin, Brian P. Brooks, Susanne Kohl, Benoit Arveiler,
Lluis Montoliu, Elizabeth C.

Engle, Frank A. Proudlock, Garima Nishad, Prateek Pani,
Girish Varma, Irene Gottlob, Mervyn G. Thomas. Genotypic and
Phenotypic Spectrum of Foveal Hypoplasia. Ophthalmology, 2022;
DOI: 10.1016/j.ophtha.2022.02.010 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220406101732.htm

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