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

European Journal of Human Genetics volume 29, pages 897–910 (2021)Cite this article

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Abstract

Since a substantial difference in the prevalence of genetic causes of rod-cone dystrophy (RCD) was found among different populations, we conducted a systematic review of the genetic findings associated with RCD in Arab countries. Of the 816 articles retrieved from PubMed, 31 studies conducted on 407 participants from 11 countries were reviewed. Next-generation sequencing (NGS) was the most commonly used technique (68%). Autosomal recessive pattern was the most common pattern of inheritance (97%) and half of the known genes associated with RCD (32/63) were identified. In the Kingdom of Saudi Arabia, in addition to RP1 (20%) and TULP1 (20%), gene defects in EYS (8%) and CRB1 (7%) were also prevalently mutated. In North Africa, the main gene defects were in MERTK (18%) and RLBP1 (18%). Considering all countries, RP1 and TULP1 remained the most prevalently mutated. Variants in TULP1, RP1, EYS, MERTK, and RLBP1 were the most prevalent, possibly because of founder effects. On the other hand, only ten Individuals were found to have dominant or X-linked RCD. This is the first time a catalog of RCD genetic variations has been established in subjects from the Arabi countries. Although the last decade has seen significant interest, expertise, and an increase in RCD scientific publication, much work needs to be conducted.

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Fig. 1: Flow chart for identifying eligible articles.
Fig. 2: Articles and variant identification techniques.
Fig. 3: Variants spectrum in analyzed individuals from Kingdom of Saudi Arabia and North Africa.
Fig. 4: A histogram showing gene prevalence in Arab individuals with sporadic and autosomal recessive rod-cone dystrophy, along with a pie-chart showing their repartition in the Arab countries.
Fig. 5: Map of the Arab countries showing the variations with possible founder effects and associated with sporadic and autosomal recessive rod-cone dystrophy.

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Data availability

The data that support the findings of this study are openly available in PubMed repository at https://www.ncbi.nlm.nih.gov/clinvar/submitters/507726.

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Author notes

  1. These authors jointly supervised: Christina Zeitz, Isabelle Audo

  2. These authors contributed equally: Hawraa Joumaa, Zamzam Mrad

Authors and Affiliations

  1. Department of Biological and Environmental Sciences, Faculty of Science, Beirut Arab University, Debbieh, 1107 2809, Lebanon

    Lama Jaffal

  2. Rammal Hassan Rammal Research Laboratory, Physiotoxicity (PhyTox), Faculty of Sciences, Lebanese University, Nabatieh, 1700, Lebanon

    Lama Jaffal, Hawraa Joumaa & Zamzam Mrad

  3. Sorbonne Universités, INSERM, CNRS, Institut de la Vision, Paris, 75012, France

    Christina Zeitz & Isabelle Audo

  4. CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC1423, 28 rue de Charenton, F-75012, Paris, France

    Isabelle Audo

  5. University College London Institute of Ophthalmology, London, EC1V 9EL, UK

    Isabelle Audo

  6. Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut, 1107 2809, Lebanon

    Said El Shamieh

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  1. Lama Jaffal
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  2. Hawraa Joumaa
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Correspondence to Said El Shamieh.

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Jaffal, L., Joumaa, H., Mrad, Z. et al. The genetics of rod-cone dystrophy in Arab countries: a systematic review. Eur J Hum Genet 29, 897–910 (2021). https://doi.org/10.1038/s41431-020-00754-0

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