Depression Genetics in Africa (DepGenAfrica): protocol for the first large-scale case-control study of major depressive disorder among continental Africans

BACKGROUND: Major Depressive Disorder (MDD) is a disabling condition that arises from the interplay of genetic and environmental risk factors. Most genetic studies of depression to date have failed to include continental African populations. As a result, risk-associated genetic variation among African populations remains undiscovered, and its potential specificity and interactions with environmental factors are unclear. METHODS: Here presented is the study protocol for the Depression Genetics in Africa (DepGenAfrica) study, which aims to 1) characterise depressive syndromes and identify the genetic architecture of MDD in 12,000 individuals (8000 cases and 4000 controls) living in Western (Nigeria), Eastern (Ethiopia) and Southern (Malawi) Africa through new data collections and collaborations with existing and ongoing projects; 2) compare the symptoms, associations and genetic architectures of MDD with other African and European ancestry populations to build a more complete global picture of its aetiology; and 3) perform downstream analyses of African MDD genetic data to investigate underlying biology and risk factors. The phenotyping battery and the data and blood sample handling procedures are outlined. DISCUSSION: The DepGenAfrica study will help fill the substantial gap in the understanding of risk mechanisms, natural clinical course and outcomes of MDD in continental African individuals. This will enhance global understanding and ensure that Africans can benefit from risk prediction algorithms, early intervention and therapeutic (including pharmacogenomic) strategies.