The genetics of rod-cone dystrophy in Arab countries: a systematic review

Jaffal, Lama; Joumaa, Hawraa; Mrad, Zamzam; Zeitz, Christina; Audo, Isabelle; Shamieh, Said El

doi:10.1038/s41431-020-00754-0

Cited by 13 publications

(14 citation statements)

References 57 publications

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“…The majority of genetically characterized individuals are reported in a single family or in few families, or as a part of cohorts located in other countries, mainly in Europe. Recently, a review on the genetics of non-syndromic rod-cone dystrophies in Arab countries disclosed the spectrum of genes and mutations identified in 26 North African Arab families, highlighting the major contribution of variants in MERTK, RLBP1, RPE65 and PDE6B genes [ 29 ]. However, in order to access the phenotypic and genetic spectrum of all non-syndromic and syndromic IRD and ION within North African families, we performed a review of the data published in the literature using PubMed and Scopus databases.…”

Section: Introductionmentioning

confidence: 99%

Clinical and genetic spectrums of 413 North African families with inherited retinal dystrophies and optic neuropathies

Bouzidi

Charoute

Charif

et al. 2022

Orphanet J Rare Dis

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Background Inherited retinal dystrophies (IRD) and optic neuropathies (ION) are the two major causes world-wide of early visual impairment, frequently leading to legal blindness. These two groups of pathologies are highly heterogeneous and require combined clinical and molecular diagnoses to be securely identified. Exact epidemiological studies are lacking in North Africa, and genetic studies of IRD and ION individuals are often limited to case reports or to some families that migrated to the rest of the world. In order to improve the knowledge of their clinical and genetic spectrums in North Africa, we reviewed published data, to illustrate the most prevalent pathologies, genes and mutations encountered in this geographical region, extending from Morocco to Egypt, comprising 200 million inhabitants. Main body We compiled data from 413 families with IRD or ION together with their available molecular diagnosis. The proportion of IRD represents 82.8% of index cases, while ION accounted for 17.8%. Non-syndromic IRD were more frequent than syndromic ones, with photoreceptor alterations being the main cause of non-syndromic IRD, represented by retinitis pigmentosa, Leber congenital amaurosis, and cone-rod dystrophies, while ciliopathies constitute the major part of syndromic-IRD, in which the Usher and Bardet Biedl syndromes occupy 41.2% and 31.1%, respectively. We identified 71 ION families, 84.5% with a syndromic presentation, while surprisingly, non-syndromic ION are scarcely reported, with only 11 families with autosomal recessive optic atrophies related to OPA7 and OPA10 variants, or with the mitochondrial related Leber ION. Overall, consanguinity is a major cause of these diseases within North African countries, as 76.1% of IRD and 78.8% of ION investigated families were consanguineous, explaining the high rate of autosomal recessive inheritance pattern compared to the dominant one. In addition, we identified many founder mutations in small endogamous communities. Short conclusion As both IRD and ION diseases constitute a real public health burden, their under-diagnosis in North Africa due to the absence of physicians trained to the identification of inherited ophthalmologic presentations, together with the scarcity of tools for the molecular diagnosis represent major political, economic and health challenges for the future, to first establish accurate clinical diagnoses and then treat patients with the emergent therapies.

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Section: Introductionmentioning

confidence: 99%

Clinical and genetic spectrums of 413 North African families with inherited retinal dystrophies and optic neuropathies

Bouzidi

Charoute

Charif

et al. 2022

Orphanet J Rare Dis

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“…Genetic counseling through pedigree analysis followed by genetic testing is available to advise the affected individuals, help them adapt, and provide them with the risk of transmitting this condition to their descendants. To expand the current knowledge and uncover disease mechanisms in RCD, many genetic studies reported novel genetic variants and showed substantial ethnic differences, which implies the need for conducting genetic studies all over the globe [ 8 , 9 , 25 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

The research output of rod-cone dystrophy genetics

Jaffal

Mrad

Ibrahim

et al. 2022

Orphanet J Rare Dis

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Non-syndromic rod-cone dystrophy (RCD) is the most common condition in inherited retinal diseases. The aim of this study was to evaluate the research output and productivity related to RCD genetics per countries as classified by the human development index (HDI), by analyzing publication frequency and citations, the choice of journals and publishers, since 2000 to date. We have also analyzed the use of next-generation sequencing (NGS) in publications originating from countries with different HDIs. One thousand four hundred articles focusing on non-syndromic RCD were downloaded and analyzed. Citations and published articles were adjusted per one million individuals. The research output is significantly higher in very high HDI countries (86% of the total publications and 95% of the citations) than countries with lower HDIs in all aspects. High and medium HDI countries published together 13.6% of the total articles worldwide and received 4.6% of the citations. On the publication level, the USA (26%), United Kingdom (10%), and Japan (7%) were the top 3 among very high HDI countries, while China (6%) and India (2%) ranked first in high and medium HDI countries respectively. On the citation level, similar profiles were found. Following adjustment for population size, Switzerland (~14%), Jordan (~ 1%) and Morocco (<0.2%) showed the highest rates of publications in very high, high and medium HDI countries respectively. Very high HDI countries published 71% of their papers in first quartile journals (first quartile in Scimago journal rank; Q1), and 23% in Q2 journals. High and medium HDI countries showed a similar profile in quartiles with ~ 40% of their papers published in Q1 journals and ~ 30% in Q2 journals. The first publication using NGS was issued in 2009 in very high HDI countries, while it appeared in 2012 in high HDI countries, and in 2017 in medium HDI countries, with a respective lag of 3 to 8 years compared to very high HDI countries. A profound gap exists between very high HDI countries and the rest of the world. To fill it in, we propose implementing NGS, supporting international collaborations, building capacities and infrastructures, improving accessibility of patients to services, and increasing national and international funding.

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“…On the other hand, the most common syndromic form is Usher syndrome (USH) (OMIM 276900), a combination of hearing loss and RP (Castiglione and Moller, 2022).Although several genetic studies have identified novel IRDs-associated genes and genetic variations, most of these associations and gene prevalence data were based on cohorts in Western Europe and North America (Smirnov et al, 2021;Colombo et al, 2021). Although the genetic basis of IRDs varies among patient cohorts, even replication for the major findings is still lacking in understudied ethnicities (Jaffal et al, 2021). Growing evidence is continuously showing the importance of better investigating these ethnicities (Amish, Mennonites, Turks, Middle Eastern…”

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confidence: 99%

“…Although several genetic studies have identified novel IRDs-associated genes and genetic variations, most of these associations and gene prevalence data were based on cohorts in Western Europe and North America ( Smirnov et al, 2021 ; Colombo et al, 2021 ). Although the genetic basis of IRDs varies among patient cohorts, even replication for the major findings is still lacking in understudied ethnicities ( Jaffal et al, 2021 ). Growing evidence is continuously showing the importance of better investigating these ethnicities (Amish, Mennonites, Turks, Middle Eastern populations, and the Ashkenazi Jews) because their structure and history of consanguinity are the most valuable and amenable for genomics studies.…”

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confidence: 99%

Editorial: The genetics of inherited retinal diseases in understudied ethnic groups: Novel associations, challenges, and perspectives

Shamieh

Maltese

2022

Front. Genet.

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Editorial on the Research TopicThe genetics of inherited retinal diseases in understudied ethnic groups: Novel associations, challenges, and perspectives Inherited retinal dystrophies (IRDs) cover a broad array of rare retinal diseases with diversify in genetic bases and phenotypes, affecting roughly as many as one in 2,000 individuals (Chen et al., 2021). Night or color blindness, tunnel vision, and later development to total blindness are all common vision impairment manifestations of IRDs that usually worsen with age (Chen et al., 2021). Cases of IRDs may be syndromic if they are coupled with extra-ocular symptoms or nonsyndromic if they are restricted to the eye (Hartong, 2006;Berson, 2006;Dryja, 2006). Interestingly, IRDs include over 20 different phenotypes (Hartong et al., 2006). The age of onset, the rate of progression, and the underlying causal genes may assist in categorizing these distinct phenotypes (Hartong et al., 2006;Perea-Romero et al., 2021). Retinitis pigmentosa (RP) (OMIM 500004), also known as rod-cone dystrophy, is the most common non-syndromic IRD, affecting around 1.5 million individuals globally (Chen et al., 2021). Other non-syndromic forms include cone-rod dystrophies (OMIM 120970), Stargardt disease (OMIM 248200), X-linked retinoschisis (OMIM 312700) and many others. On the other hand, the most common syndromic form is Usher syndrome (USH) (OMIM 276900), a combination of hearing loss and RP (Castiglione and Moller, 2022).Although several genetic studies have identified novel IRDs-associated genes and genetic variations, most of these associations and gene prevalence data were based on cohorts in Western Europe and North America (Smirnov et al., 2021;Colombo et al., 2021). Although the genetic basis of IRDs varies among patient cohorts, even replication for the major findings is still lacking in understudied ethnicities (Jaffal et al., 2021). Growing evidence is continuously showing the importance of better investigating these ethnicities (Amish, Mennonites, Turks, Middle Eastern

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The genetics of rod-cone dystrophy in Arab countries: a systematic review

Cited by 13 publications

References 57 publications

Clinical and genetic spectrums of 413 North African families with inherited retinal dystrophies and optic neuropathies

Clinical and genetic spectrums of 413 North African families with inherited retinal dystrophies and optic neuropathies

The research output of rod-cone dystrophy genetics

Editorial: The genetics of inherited retinal diseases in understudied ethnic groups: Novel associations, challenges, and perspectives

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