Asked in Conditions and DiseasesDemographicsAnemiaSickle-Cell Disease
Conditions and Diseases
How many people die of sickle cell?
What is the effects of natural selection on the frequency of the sickle cell allele in an area where malaria occurs?
People who have a sickle cell allele are immune to malaria, so the people with the one sickle cell allele have a greater chance of surviving malaria than people who do not have the allele. Through natural selection the frequency of people with the sickle cell allele will increase because they survive and are able to pass on their gene. More people will die who do not have the allele, so they are unable to pass on their genes.
What is the probability that two unaffected individuals will have a sickle cell affected offspring?
How does balancing selection affect the sickle cell allele in central Africa?
The sickle cell allele can be maintained in the central African population, above the frequency of gene mutation (balancing selection), because the heterozygous sickle cell individuals have an advantage in lifespan, in this malaria stricken region, over the homozygous alternatives. Homozygous sickle-sickle individuals die early from the sickle cell disease. Homozygous nonsickle-nonsickle die early from malaria. The heterozygous sickle-nonsickle have a higher survival against malaria and therefore the sickle cell allele is balanced selected.
Is it good to have sickle cell anemia?
Yes, and no. No, because when you do have sickle cell anemia, your irregular blood shape interferes with the blood's ability to carry oxygen and pass through narrow openings such as the capillary. People who have sickle cell die relatively early because of the organ damage and lack of oxygen caused by the blood's irregularity. Yes, because it has been found that people with sickle cell anemia are protected against malaria.
What does sickle cell anemia classified as?
It is a genetic disorder. However... It is also a protection against malaria. For example, if a person were born in an area where malaria is present, he or she would likely die from the disease, unless he or she inherited 1 sickle cell gene. Malaria viruses reproduce in the red blood cells. The parent virus invades a cell, and uses the cell as a host to grow more viruses. With 1 sickle cell gene, malaria viruses that invade a red cell are quickly destroyed, since the red cell collapses, preventing the virus from reproducing. But with 2 sickle cell genes, red cells collapse too easily; just a bruise can cause someone to become anemic when too many red cells collapse. In the real world, people with no sickle cell genes died from malaria. People with 1 sickle cell gene survived. People with 2 sickle cell genes died from sickle cell anemia. It was natures way of assuring that at least half of the population survive, but it is certainly a difficult thing to live with today, now that we can more easily treat malaria.
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How does a person with sickle-cell allele differ from a person with two sickle-cell alleles?
If a person has a single sickle cell allele they will have some sickles red blood cells, and some normal red blood cells. This is the origami purpose that this evolved for. If a person had a single sickle cell allele, they will be mostly resistant to malaria. This is why sickle cell anemia is most prevalent in areas of the world where malaria is common. However, if a person has two sickle cell anemia alleles, they will have ONLY sickled red blood cells. The "sickling" of the red blood cells is caused by a mutation in the protien that the gene codes for. That protein is hemoglobin, which carries oxygen through the blood. If a person has sickle cell anemia, parts of their body wil not get enough oxygen. They can pass out, loose sensation in the limb, or even die from it. In short, a person with two alleles is sick, and a person with one allele is not.
What is the benefit of sickle cell anemia to Africans with malaria?
In haemoglobin, there are four polypeptide chains that make it's structure, 2 (A) chains and 2 (B) chains. Sickle-Cell Anemia is caused by a mutation the (B) chain that makes the haemoglobin molecules stick to each other and form fibres inside the red blood cell (RBC). Instead of a circular disc shaped RBC we now have a sickle shaped cell. This means transport of oxygen is very innefficient and the disease can cause death. However, in areas with a high malaria rate, heterozygous sickle-cell anaemics (with some sickle shaped AND normal RBCs) are naturally selected because the protozoan (what causes the disease) is unable to live inside the red blood cell due to the fibres formed from the mutation, the cells are more fragile and they have a shorter life span than normal RBCs. This means that people with heterozygous alleles for sickle-cell anaemia benefit against malaria and will survive to reproduce, which increases the allele frequency of the sickle-cell anaemia allele. Those with homozygous sickle-cell anaemia and those with homozygous normal haemoglobin are selected against as the first usually die of the sickle-cell anaemia, and the latter contract malaria. NB. Mutations are rare occurrences. It is even rarer for a mutation to give selective advantage. This mutation for sickle-cell anaemia did not happen to 'cure' or prevent malaria, it was a random occurrence that coincidentally gave a selective advantage against malaria.
How is it possible for only some races to have certain diseases or deformities like Sickle-Cell Anemia for African-Americans and Head Lice for Caucasians?
Some diseases are the result of adaptations to an environment. As it turns out, Sickle Cell Anemia is an adaptation to Malaria. If a person has a single copy of the Sicke Cell gene, he or she is protected against Malaria. If he or she has NO copies of the gene, he or she will die if exposed to Malaria. If he or she has two copies of the gene he or she will die from Sickle Cell Anemia. Malaria was fatal to pretty much everyone. The genetic mutation allowed about half of the population of the region to live. Today, we no longer have the threat from Malaria so now Sickle Cell Anemia becomes the problem.
Is it only males that can get sickle cell?
Can you die of Sickle cell anemia?
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Asked in Anemia, Sickle-Cell Disease
Does sickle cell mess with the mind?
I highly doubt it. Sickle cell only affects blood cells and their ability to hold oxygen. The only way for it to affect the mind would be for it to significantly reduce the amount of oxygen that was going to the brain, thus causing delirium. But if that were the case, after a month or so, a baby would die anyways, and would never live to reach Adulthood. So no, Sickle cell will not mess with the mind, and any case where it does so would be lethal in childhood.
Can you die from sickle cell disease?