Even harmful mutations do not get eliminated from gene pool due tio

Even harmful mutations do not get eliminated from gene pool due to

The reason why some mutations which are harmful do not get eliminted from gene pool is that :

Gene mutation is due to :

It is said, that the harmful alleles get eliminated from population over a period of time, yet sickel cell anaemia is persisting in human population. Why?

It is said, that the harmful alleles get eliminated from population over a period of time, yet sickle-cell anaemia is persisting in human population. Why?

It is said, that the harmful alleles get eliminated from population over a period of time, yet sickle-cell anaemia is persisting in human population. Why?

It is said that the harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population. Why ?