Sickle cell anemia is a condition where the red blood cells are deformed. which is affected by sickle cell anemia?

Sickle cell anemia is a hereditary disease which provides less oxygen to cells due to a change in the shape of red blood cells which fails to carry oxygen to cells.  

In sickle cell anemia, the effected or mutated part is the beta gene that normally makes hemoglobin but due to the mutation in the amino acid, the protein formed is defected and fails to perform its normal function.

As mentioned above, it is a heredity diseases and pass from generations to generations.