A blood test can check for the defective form of hemoglobin that underlies sickle cell anemia. In the United States, this blood test is part of routine newborn screening. But older children and adults can be tested, too. In adults, a blood sample is drawn from a vein in the arm.

Hemoglobin is a protein in red blood cells that carries oxygen throughout the body. With SCD, the hemoglobin forms into stiff rods within the red blood cells. This changes the shape of the red blood cells. The cells are supposed to be disc-shaped, but this changes them into a crescent, or sickle, shape.

A mutation in HBB results in a change in one of the bases? in the DNA? sequence from an A to a T. This then changes the amino acid? in the haemoglobin protein from glutamic acid to valine. This causes the body to produce a new form of haemoglobin called HbS, which behaves very differently to regular haemoglobin (HbA).

The mutation in the HBB gene in sickle cell anemia changes one of the amino acids, the building blocks of proteins, in the beta chain of hemoglobin. This defect causes the hemoglobin protein to stick together and form stiff fibers. These fibers distort the shape of the red blood cells and make them more fragile.

In sickle cell anemia, the abnormal hemoglobin causes red blood cells to become rigid, sticky and misshapen. Both mother and father must pass the defective form of the gene for a child to be affected. If only one parent passes the sickle cell gene to the child, that child will have the sickle cell trait.

Sickle cell disease is an inherited blood disorder usually diagnosed at birth. Most people with the disease begin to show symptoms by 4 months of age or shortly thereafter.

But people born with sickle cell disease have sickle-shaped blood cells that usually live no more than 20 days. These sickled cells can get stuck in blood vessels, blocking blood flow. Less blood flow can damage the body’s organs, muscles, and bones, sometimes leading to life-threatening conditions.