Multiple choice Which amino acid change causes sickle cell anaemia? Threonine to valine Glutamic acid to valine Glutamic acid to isoleucine Alanine to valine Glutamic acid to alanine Reveal answer Fill a bubble to check yourself B Correct answer Explanation The change of glutamic acid to valine in the sixth position of beta globin chain of haemoglobin causes sickle cell anaemia.