Question

Why does sickle-cell anaemia persist in the human population when it is believed that the harmful alleles get eliminated from the population after a certain time?​

Answer 1

Answer:

The harmful alleles get eliminated from population over a period of time yet sickle cell anaemia is persisting in human population because SCA is a harmful condition which is also a potential saviour from malaria.Those with the benign sickle trait possess a resistance to malarial infection. The pathogen that causes the disease spends part of its cycle in the red blood cells and triggers an abnormal drop in oxygen levels in the cell. In carriers this drop is sufficient to trigger the full sickle-cell reaction which leads to infected cells being rapidly removed from circulation and strongly limiting the infection’s progress. These individuals have a great resistance to infection and have a greater chance of surviving outbreaks. This resistance to infection is the main reason the SCA allele and SCA disease still exist. It is found in greatest frequency in populations where malaria was and is still often a serious problem.

Answer 2

• The harmful alleles get eliminated from population over a period of time yet sickle cell anaemia is persisting in human population because SCA is a harmful condition which is also a potential saviour from malaria.
• This resistance to infection is the main reason the SCA allele and SCA disease still exist.

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