A Review of Sickle Cell Disease: Then and Now

Abstract

Sickle Cell Disease (SCD) is a group of disorders associated with mutations in the β-globin (HBB) gene and defined by the presence of haemoglobin S (HbS). SCD affects millions of people worldwide and is prevalent among people whose ancestors originated from places where malaria was or is still endemic. More than 90% of individuals born with SCD live in low- and middle-income countries (LMICs). Over 50% of persons with SCD are accounted for by Nigeria, India and the Democratic Republic of Congo (DRC) alone. Premarital counselling and maternal carrier screening are crucial for effective prevention of SCD, while neonatal screening aids in early diagnosis. Although significant strides have been achieved with SCD diagnosis and therapy in high-income countries, LMICs still lag far behind in terms of implementation of these advances. For example, in Sub-Saharan Africa (SSA), newborn screening is rare, and in India, dried blood spot screening is gaining traction. Also, the most commonly used SCD diagnostic techniques in Nigeria and the DRC are alkaline cellulose acetate Hb electrophoresis and the Emmel test (sickling test), respectively. In contrast, in India, it is high-performance liquid chromatography (HPLC). Challenges such as inadequate blood supply, unavailability of stem cell transplant (only in the DRC), suboptimal availability of hydroxyurea, and the unavailability of l-glutamine, crizanlizumab and novel gene therapies are common to the aforementioned countries. Nonetheless, efforts are underway to improve SCD diagnosis and treatment in these countries. This review gives a succinct overview of SCD, with a focus on the aforementioned LMICs.