Sickle Cell Anemia - Molecular Mechanism

The Sickle Anaemia also called as sickle cell disease is a genetic disorder of Red blood cells where the Red blood cells can transform into shapes like sickle or crescent.
Sickle-cell disease occurs when a person inherits two abnormal copies of the haemoglobin gene, one from each parent. This gene occurs in chromosome 11. Several subtypes exist, depending on the exact mutation in each haemoglobin gene.An attack can be set off by temperature changes, stress, dehydration, and high altitude.A person with a single abnormal copy does not usually have symptoms and is said to have sickle-cell trait.
In Sickle Cell Anaemia the Glutamic acid is replaced by valine in its polypeptide chain , it is actually a point mutation at DNA level where Adenine is replaced by thymine in DNA strand , which later on incorporates codon for valine instead of Glutamic acid in mRNA chain.
The shape of defective Haemoglobin is crystalline in nature which is called Tactoids.