ABSTRACT
What happens to haemoglobin in sickle cell anaemia? In sickle cell disease there is an abnormal β polypeptide chain due to a genetic mutation in the amino acid sequence where the amino acid valine is replaced by glutamic acid. In the heterozygous state this confers an advantage against malaria as the shortened lifespan of the erythrocyte prevents the blood-borne phase of the mosquito from completing its life cycle. In the homozygous state the abnormal haemoglobin is susceptible to forming solid nonpliable sickle-like structures when exposed to low PaO2, causing the erythrocytes to obstruct the microcirculation, leading to painful crises and infarcts.
