#101 Sickle cell anaemia and its incidence to that of malaria
Sickle cell anaemia is caused by a mutation in the blood pigment haemoglobin. When the faulty haemoglobin is present in a red blood cell, it causes the cell to deform and become sickle-shaped, especially when oxygen levels in the blood become low.
Normal and sickle red blood cells.
Credit: Wellcome Trust, UK
In this state the sickled red blood cells are less efficient at transporting oxygen and more likely to become stuck in a capillary, preventing blood flow.
The faulty allele is dominated by the allele for normal haemoglobin, but still has some effect in a heterozygous genotype.
The possible genotypes are:
Malaria is a life-threatening disease caused by a parasite that invades red blood cells. The parasite is carried by some species of mosquito.
Video: Sickle cell disease
The faulty allele is dominated by the allele for normal haemoglobin, but still has some effect in a heterozygous genotype.
The possible genotypes are:
- HNHN normal haemoglobin, no anaemia
- HNHn some abnormal haemoglobin, sickle cells trait (not life-threatening)
- HnHn abnormal haemoglobin, sickle cells anaemia (life-threatening)
Malaria is a life-threatening disease caused by a parasite that invades red blood cells. The parasite is carried by some species of mosquito.
- A person who is heterozygous (HNHn ) for sickle cell anaemia has protection from malaria, because the malaria parasite is unable to invade an reproduce in the sickle cells.
- A person who is homozygous for sickle cell anaemia (HnHn) also has protection, but is at high risk of dying form sickle cell anaemia.
- A person with normal haemoglobin (HNHN) in a malarial country is at high risk of contracting malaria.
Video: Sickle cell disease
Video: What is Sickle cell anaemia
Video: Evolution of sickle cell malaria
