Question

In Spite of the great disadvantages of sickle cell anemia it has a high frequency in some parts of Africa. It is because of the reason that
(a) Person having sickle cell anaemia is resistant to malaria.
(b) In South Africa oxygen concentration is very high.
(c) It is a case of genetic drift.
(d) All of the above

Answer 1

Hint: Sickle Cell anemia is a genetic disorder in which the shape of the cell changes from oval to sickle if they inherit two faulty copies of the gene for the oxygen-carrying protein hemoglobin. Due to the faulty gene persists because even carrying one copy of it confers some resistance to a parasitic disease.

Complete answer:
A health issue like sickle cell anemia is one of a group of disorders that are known as sickle cell disease. This anemic disease is an inherited red blood cell disorder in which there aren't enough healthy red blood cells to carry oxygen throughout your body. Normally the flexible round red blood cells move easily through blood vessels but in the case of sickle cell anemia, the red blood cells took shape like sickles or crescent moons. These sickle-shaped blood cells are rigid and sticky which can get stuck in small blood vessels, and lead to slow or block blood flow and oxygen to parts of the body. The scientist Michael Lanzer and his colleagues at Heidelberg University in Germany and the Biomedical Research Center Pietro Annigoni in Ouagadougou, Burkina Faso, discovered that Sickle cells infected with Plasmodium falciparum collapse and prevent the parasite from interfering with the cell's actin proteins, protecting the host against malaria.

So the correct answer is option a) Person having sickle cell anaemia is resistant to malaria.

Additional information:
1) We can observe the signs of the disease around 5 months of age which include anemia, episodes of pain, swelling of hands and feet, delayed growth or puberty, frequent infection, vision problem.
2) This anemia is caused by a mutation in the gene that directs our body to make the iron-rich compound that makes blood red and enables red blood cells to carry oxygen from lungs throughout the body (hemoglobin).
3) A Cooperative Study of Sickle Cell Disease that was published in the New England Journal of Medicine in 1994 is often used by someone as a baseline for the study. The mentioned study monitored patients in the U.S. and estimated the median life expectancy of women with sickle cell anemia to 48 years and men 42 years between the years 1978 and 1988.

Note:
Both parents must carry a sickle cell gene for a baby to be born with sickle cell anemia, if only one parent passes the sickle cell gene to the child, that child will have the sickle cell trait. Such people with one normal hemoglobin gene and one defective form of the gene, people with the sickle cell trait make both normal hemoglobin and sickle cell hemoglobin, and also their blood might contain some sickle cells, but they generally don't show symptoms. Sickle cell anemia most commonly affects black people in the United States.