The mutation that causes sickle cell disease changes a Valine to a Glutamic acid at position 6 of the coding region for beta-hemoglobin

The mutation that causes sickle cell disease changes a Valine to a Glutamic acid at position 6 of the coding region for beta-hemoglobin. What type of mutation is this? a nonsense mutation. O a codon deletion a single-base deletion a missense mutation