Yandiswa Y Yako1, Magellan Guewo-Fokeng2, Eric V Balti3, Nabila Bouatia-Naji4, Tandi E Matsha5, Eugene Sobngwi6, Rajiv T Erasmus7, Justin B Echouffo-Tcheugui8, Andre P Kengne9. 1. Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa; Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Cape Town, South Africa. 2. Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde, Cameroon. 3. Diabetes Research Center, Faculty of Medicine and Pharmacy, Brussels Free University, Brussels, Belgium. 4. INSERM UMR970 Paris Cardiovascular Research Center, 56 rue Leblanc F-75015 Paris, France; Paris Descartes University, PRES Paris Sorbonne, 12 rue de l'école de medecine F75006 Paris, France. 5. Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Cape Town, South Africa. 6. Department of Internal Medicine, Faculty of Medicine and Biomedical Sciences, University of Yaounde I, Yaounde, Cameroon. 7. Division of Chemical Pathology, Faculty of Medicine and Health Sciences, National Health Laboratory Service (NHLS), University of Stellenbosch, Cape Town, South Africa. 8. Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA; Department of Medicine, MedStar Health System, Baltimore, MD, USA. 9. Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa; Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa; The George Institute for Global Health, The University of Sydney, Sydney, NSW, Australia. Electronic address: andre.kengne@mrc.ac.za.
Abstract
BACKGROUND: Type 2 diabetes (T2D) is growing faster in Africa than anywhere else, driven by the dual effects of genetic and environmental factors. We conducted a systematic review and meta-analyses of published studies on genetic markers of T2D in populations within Africa. METHODS: Multiple databases were searched for studies of genetic variants associated with T2D in populations living in Africa. Studies reporting on the association of a genetic marker with T2D or indicators of glycaemia were included. Data were extracted on study design and characteristics, genetic determinants, effect estimates of associations with T2D. FINDINGS: Overall, 100 polymorphisms in 57 genes have been investigated in relation with T2D in populations within Africa, in 60 studies. Almost all studies used the candidate gene approach, with >88% published during 2006-2014 and 70% (42/60) originating from Tunisia and Egypt. Polymorphisms in ACE, AGRP, eNOS, GSTP1, HSP70-2, MC4R, MTHFR, PHLPP, POL1, TCF7L2, and TNF-α gene were found to be associated with T2D, with overlapping effect on various cardiometabolic traits. The polymorphisms investigated in multiple studies mostly had consistent effects across studies, with only modest or no statistical heterogeneity. Effect sizes were modestly significant [e.g., odd ratio 1.49 (95%CI 1.33-1.66) for TCF7L2 (rs7903146)]. Underpowered genome-wide studies revealed no diabetes risk loci specific to African populations. INTERPRETATION: Current evidence on the genetic markers of T2D in African populations mostly originate from North African countries, is overall scanty and largely insufficient to reliably inform the genetic architecture of T2D across Africa.
BACKGROUND:Type 2 diabetes (T2D) is growing faster in Africa than anywhere else, driven by the dual effects of genetic and environmental factors. We conducted a systematic review and meta-analyses of published studies on genetic markers of T2D in populations within Africa. METHODS: Multiple databases were searched for studies of genetic variants associated with T2D in populations living in Africa. Studies reporting on the association of a genetic marker with T2D or indicators of glycaemia were included. Data were extracted on study design and characteristics, genetic determinants, effect estimates of associations with T2D. FINDINGS: Overall, 100 polymorphisms in 57 genes have been investigated in relation with T2D in populations within Africa, in 60 studies. Almost all studies used the candidate gene approach, with >88% published during 2006-2014 and 70% (42/60) originating from Tunisia and Egypt. Polymorphisms in ACE, AGRP, eNOS, GSTP1, HSP70-2, MC4R, MTHFR, PHLPP, POL1, TCF7L2, and TNF-α gene were found to be associated with T2D, with overlapping effect on various cardiometabolic traits. The polymorphisms investigated in multiple studies mostly had consistent effects across studies, with only modest or no statistical heterogeneity. Effect sizes were modestly significant [e.g., odd ratio 1.49 (95%CI 1.33-1.66) for TCF7L2 (rs7903146)]. Underpowered genome-wide studies revealed no diabetes risk loci specific to African populations. INTERPRETATION: Current evidence on the genetic markers of T2D in African populations mostly originate from North African countries, is overall scanty and largely insufficient to reliably inform the genetic architecture of T2D across Africa.
Authors: Maria S Bornman; Natalie H Aneck-Hahn; Christiaan de Jager; Gesina M Wagenaar; Hindrik Bouwman; Irene E J Barnhoorn; Sean M Patrick; Laura N Vandenberg; Andreas Kortenkamp; Bruce Blumberg; Sarah Kimmins; Bernard Jegou; Jacques Auger; Joseph DiGangi; Jerrold J Heindel Journal: Environ Health Perspect Date: 2017-08-22 Impact factor: 9.031