Sickle cell trait is caused by abnormal hemoglobin called sickle hemoglobin or Hb S. Sickle hemoglobin is as a result of a point mutation in the beta globin chain. This point mutation replaces A with T at codon 6 of beta hemoglobin chain. This causes the switch from glutamic acid to valine amino acid.
How is HbS formed?
HbS arises from a mutation substituting thymine for adenine in the sixth codon of the beta-chain gene, GAG to GTG. This causes coding of valine instead of glutamate in position 6 of the Hb beta chain. The resulting Hb has the physical properties of forming polymers under deoxy conditions.
What type of mutation is the sickle hemoglobin mutation?
Sickle cell anemia is the result of a point mutation in the hemoglobin gene. Sickle cell hemoglobin (HbS) causes red blood cells to form a sickle shape. People who inherit one sickle cell gene and one normal gene have sickle cell trait.
What causes HbS to sickle?
Sickle cell disease is caused by a variant of the beta-globin gene called sickle hemoglobin (Hb S). Inherited autosomal recessively, either two copies of Hb S or one copy of Hb S plus another beta-globin variant (such as Hb C) are required for disease expression.
What blood type carries sickle cell?
It is an inherited condition in which both hemoglobin A and S are produced in the red blood cells, always more A than S. Individuals with sickle cell trait are generally healthy.
Is Sickle Cell Anemia a substitution mutation?
Sickle cell is a homogenous genetic anemia caused when an abnormal gene (hemoglobin S or HbS) causes the substitution of the amino acid valine, for another, glutamic acid (Amundsen et al., 1984).
Is Sickle Cell Anemia a deletion mutation?
Sickle-cell anemia results from an A leads to T transversion in the second nucleotide of codon 6 of the beta-globin gene. We now report an uncommon beta-thalassemia gene that contains a deletion of this nucleotide.
What are the examples of mutation?
Types of Changes in DNA
|Class of Mutation||Type of Mutation||Human Disease(s) Linked to This Mutation|
|Point mutation||Substitution||Sickle-cell anemia|
|Insertion||One form of beta-thalassemia|
|Chromosomal mutation||Inversion||Opitz-Kaveggia syndrome|
What causes a deletion mutation?
A deletion mutation occurs when a wrinkle forms on the DNA template strand and subsequently causes a nucleotide to be omitted from the replicated strand (Figure 3). Figure 3: In a deletion mutation, a wrinkle forms on the DNA template strand, which causes a nucleotide to be omitted from the replicated strand.