sickle cell disease (SCD)
Last reviewed 10/2021
Sickle cell disease (SCD) is a group of inherited, multisystemic conditions with episodes of acute illness and progressive organ damage. It is characterized by the occurrence of the sickle mutation (1,2).
- mutation in the beta globin gene results in substitution of valine for glutamine at the sixth position in the beta-subunit of a Hb molecule and leads to the production of abnormal beta-globin chain. This alpha2-S2 tetramer is called sickle haemoglobin molecule (HbS) (1)
- the disease shows an autosomal recessive inheritance (3), all SCD genotypes contain at least one sickle gene in which HbS comprises at least half of the haemoglobin present (4)
- in sickle cell anaemia (homozygous SCD) - 80-99% of the haemoglobin is HbS, with most of the remainder being fetal haemoglobin (HbF)
When exposed to low oxygen tensions or acidaemia non-covalent polymerisation of HbS takes place, resulting in distortion and sickling of red cells.
Distorted red cells cannot negotiate capillaries, with two effects:
- cells are prematurely destroyed, especially in the spleen, reducing the mean life of a red cell to 10-12 days (4)
- blood supply to tissues may be occluded, leading to infarction
- advice from the UK National Screening Committee on antenatal screening for sickle cell....click here
Patient information leaflets from UK National Screening Committee:
is sickle cell disease?..click here
do people get sickle cell disease?..click here
should I think about being tested for sickle cell disease?..click here
- Results of Newborn Blood-Spot screening reveal baby is a carrier of a sickle cell gene ? sometimes called trait Hb AS..click here
- (1) Sickle Cell Society 2008. Standards for the clinical care of adults with sickle cell disease in the UK
- (2) Rees DC, Williams TN, Gladwin MT. Sickle-cell disease Lancet. 2010 11;376(9757):2018-31
- (3) American Academy of Pediatrics. Health supervision for children with sickle cell disease. Pediatrics. 2002;109(3):526-35
- (4) NHS Antenatal and Newborn Screening Programmes 2010. Sickle cell disease in childhood: standards and guidelines for clinical care
- (5) Drug and Therapeutics Bulletin (2001), 39 (5), 33-37.