Mutation

**Contents:**

 * 1) Introduction>
 * 2) **__Mutation__**
 * 3) Signs and Symptoms
 * 4) Heredity
 * 5) Treatment Methods
 * 6) Screening
 * 7) Interesting Facts
 * 8) Links
 * 9) Bibliography

__Mutation__
Sickle cell anemia is an inherited disease caused by a genetic mutation (point mutation). Genes are distinct sequences of nucleotides that form part of a chromosome. In our body, there are 46 chromosomes in total, or 23 pairs in each cell within our body. The chromosome that is responsible for the body's regular hemoglobin production is the 11th pair of the chromosome. The gene that is associated with sickle cell anemia is the hemoglobin, beta, or HBB in short which is found in region 15.5 on the short arm of chromosome 11.

> hemoglobin is a red protein responsible for transporting oxygen in the blood.

Several hundreds of different variants of HBB gene are known, but Hb S is the one that causes sickle cell anemia most of the times. At the position of the sixth amino acid in the polypeptide chain of Hb S, a substitution mutation takes place. It changes from the original GAG (glutamate) to GUG (valine).

When the red blood cells return to the lungs where hemoglobin can bind oxygen, the long chains of Hb S molecules break apart into single molecules. Later on, the cell membranes of the red blood cells become rigid. When the shape of the cells is distorted, they are no longer able to carry oxygen, resulting in blockage of small blood vessels.

Signs and Symptoms-->