Question

What genetic mutation is sickle cell anemia caused by?

Answer 1

Sickle cell disease is caused by a mutation in the hemoglobin-Beta gene found on chromosome 11.

Answer 2

"Sickle-cell anemia is caused by a point mutation in the β-globin chain of hemoglobin."

More can be found on the wikipedia page about point mutation if you want more information about the specifics.