Sickle cell disorder (SCD) is the commonest inherited disorder in tropical Africa and, Nigeria–the most populous African country–contributes about half of the estimated 300,000 newborns with SCD annually.
SCD occurs when an individual inherits the variant sickle haemoglobin (Hb S) from one parent and another variant Hb from the other parent. The latter variant Hb may also be an Hb S or may be a different variant Hb such as Hb C, Hb O-Arab, or reduced or absent production of the β-haemoglobin chain, etc. The inheritance of Hb S from both parents i.e. Hb SS, is referred to as sickle cell anaemia and it is the commonest and most severe form of SCD. Thus SCD includes Hb SS, Hb SC, Hb S-β thalassaemia etc. Hb CC also occurs and although it is without Hb S, it is also an inherited Hb disorder which we should learn to recognize and attend to.