why do alot of africans suffer from sickle cell anaemia?

Question

why do alot of africans suffer from sickle cell anaemia?

Answer 1

Sickle-cell disease is a general term for a group of genetic disorders caused by sickle hemoglobin (HbS). In many forms of the disease, the red blood cells change shape upon deoxygenation because of polymerization of the abnormal sickle hemoglobin.

HbN and HbS are alleles which are alternative forms of gene. All humans have 2 alleles for every gene (one from each parent).
Normal healthy people have HbN HbN (HbN=normal hemoglobin).
Carriers have HbN HbS (HbS=sickle hemogloblin).
People suffering from sickle cell anaemia have HbS HbS.

In people heterozygous for HbS (carriers), the polymerization problems are minor, hence they don't suffer the effects of sickle cell anaemia. In people homozygous for HbS, the presence of long chain polymers of HbS distort the shape of the red blood cell, from a smooth donut-like shape to ragged and full of spikes, making it fragile and susceptible to breaking within capillaries. Carriers only have symptoms if they are deprived of oxygen (for example, while climbing a mountain) or while severely dehydrated.

The sufferers of the illness have a reduced life span. It is believed that carriers (sickle cell trait) are relatively resistant to malaria. Since the gene is incompletely recessive, carriers have a few sickle red blood cells at all times, not enough to cause symptoms, but enough to give resistance to malaria. Because of this, heterozygotes (HbS HbN) have a higher fitness than either of the homozygotes (HbN HbN & HbS HbS). This is known as heterozygote advantage. Those with HbN HbN are susceptible to malaria while those with HbS HbS will suffer from sickle cell anaemia.

The malaria parasite has a complex life cycle and spends part of it in red blood cells. In a carrier, the presence of the malaria parasite causes the red blood cell to rupture, making the plasmodium unable to reproduce. Further, the polymerization of Hb affects the ability of the parasite to digest Hb in the first place. Therefore, in areas where malaria is a problem, people's chances of survival actually increase if they carry sickle cell anaemia.

Due to the above phenomenon, the illness is still prevalent, especially among people with recent ancestry in malaria-stricken areas, such as Africa, the Mediterranean, India and the Middle East. In fact, sickle-cell anemia is the most common genetic disorder among African Americans; about 1 in every 12 is a carrier.

Answer 2

Sickle Cell Anaemia, and other blood disorders, Like Thallasemia, are genetic blood disorders. Meaning: Genes carry the information, and many ethnicities are have those common genes. The gene that causes sickle cell anaemia is found mainly in groups of people whose ancestors have originated from Africa.

Over time, people who had the sickle cell gene in areas that had malaria-infected mosquitoes remained alive, as the malaria virus cannot live in the infected red blood cells (not enough oxygen). When these people survived, they allowed the gene to be passed down to various generations. Note that many of these areas aof malaria are in Africa. Eventually, many Afircans migrated and the genes migrated with them.

This is why Sickle Cell Anaemia is in many places outside of Africa.

Answer 3

Sickle cell anemia occurs when two parents who have sickle cell trait have a child. Having the trait is a good thing in places where malaria is high. Malaria has difficulty living in cells that are sickle shaped and is thus protective. When one has the disease however too many of the cells are sickle shaped and get lodged in the organs of the body causing severe pain. Africans, mediterranians, and some Italians as well as others in that region are known to carry the trait.

Answer 4

Many africans suffer from sickle cell anemia because it is a genetic adaptation that fights the disease malaria. Malaria is a serious disease on the continent of Africa, and therefore the body manufactures sickled red blood cells to fight the disease. Sickle cell is an inherited recessive illness.

Answer 5

Sickle cell anemia is a genetic trait that tends to run in people of African descent. As you probably know, malaria - a blood born disease transmitted by mosquitoes - is prevalent in Africa. As it turns out, people who have sickle cells are protected from infection with malaria. So over time, people without sickle cell got infected with malaria and some of them died, while those with the sickle cell trait were protected and lived - to produce more children with the trait. It's natural selection!

Answer 6

I have heard people say malaria is responsible for this.Malaria created a selection pressure for people with sickle cell disease in Africa as the people with sickle cell disease were able to survive malaria as they have an advantage over normal people in surviving Malaria and thus were able to pass down their genes and thus we have so many people from Africa having sickle cell disease.Thats just a theory though but might very well be true.

Answer 7

i understand you're pertaining to that fool that keeps asking if Obama has sickle-cellular. the guy won't examine this guidance for to him that's humorous. Evil human beings would be unable to be stopped with guidance. regrettably, yet thank you for attempting.