Answer:
Point mutation
Step-by-step explanation:
Change in single nucleotide of the DNA is referred to as point mutation. In hemoglobin, point mutation replaces the "adenine base" by "thymine" at the 17th nucleotide of the hemoglobin beta gene. This single nucleotide mutation replace the codon GAG (glutamic acid) to GTG (which encodes amino acid valine) and causes sickle cell anemia.