Identifying the genetic causes of developmental disorders and intellectual disability in Africa: a systematic literature review

Fiona Baine-Savanhu; Shelley Macaulay; Nadja Louw; Alanna Bollweg; Kaitlyn Flynn; Mhlekazi Molatoli; Patracia Nevondwe; Heather Seymour; Nadia Carstens; Amanda Krause; Zané Lombard

doi:10.3389/fgene.2023.1137922

Identifying the genetic causes of developmental disorders and intellectual disability in Africa: a systematic literature review

Front Genet. 2023 May 10:14:1137922. doi: 10.3389/fgene.2023.1137922. eCollection 2023.

Authors

Affiliations

¹ Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
² Genomics Platform, South African Medical Research Council, Cape Town, South Africa.

Abstract

Objective: Genetic variants cause a significant portion of developmental disorders and intellectual disabilities (DD/ID), but clinical and genetic heterogeneity makes identification challenging. Compounding the issue is a lack of ethnic diversity in studies into the genetic aetiology of DD/ID, with a dearth of data from Africa. This systematic review aimed to comprehensively describe the current knowledge from the African continent on this topic. Method: Applicable literature published up until July 2021 was retrieved from PubMed, Scopus and Web of Science databases, following PRISMA guidelines, focusing on original research reports on DD/ID where African patients were the focus of the study. The quality of the dataset was assessed using appraisal tools from the Joanna Briggs Institute, whereafter metadata was extracted for analysis. Results: A total of 3,803 publications were extracted and screened. After duplicate removal, title, abstract and full paper screening, 287 publications were deemed appropriate for inclusion. Of the papers analysed, a large disparity was seen between work emanating from North Africa compared to sub-Saharan Africa, with North Africa dominating the publications. Representation of African scientists on publications was poorly balanced, with most research being led by international researchers. There are very few systematic cohort studies, particularly using newer technologies, such as chromosomal microarray and next-generation sequencing. Most of the reports on new technology data were generated outside Africa. Conclusion: This review highlights how the molecular epidemiology of DD/ID in Africa is hampered by significant knowledge gaps. Efforts are needed to produce systematically obtained high quality data that can be used to inform appropriate strategies to implement genomic medicine for DD/ID on the African continent, and to successfully bridge healthcare inequalities.

Keywords: Africa; developmental disorder; genetic disorder; genetic testing; intellectual disability.

Publication types

Systematic Review

Grants and funding

Research reported in this publication was supported by the National Institute of Mental Health of the National Institutes of Health under Award Number U01MH115483. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.