These Sickled Cells

What Are the Types of
Sickle Cell Disease?

Hemoglobin is the protein in RBCs that
carries oxygen. It is made up of two alpha
chains and two beta chains. These are
made by the alpha and beta genes. The
four main types of sickle cell anemia are
caused by different mutations in these

Hemoglobin SS Disease

Hemoglobin SS disease is the most
common type of sickle cell disease. It
occurs when you inherit copies of the
hemoglobin S gene from both parents.
This forms hemoglobin known as Hb SS.

Hemoglobin SC Disease

Hemoglobin SC disease is the second
most common type of sickle cell disease.
It occurs when you inherit the Hb C gene
from one parent and the Hb S gene from
the other. Individuals with Hb SC have
similar symptoms to individuals with Hb
SS. However, the anemia is less severe.

Hemoglobin SB+ (Beta) Thalassemia

Hemoglobin SB+ (Beta) thalassemia
affects beta globin gene production. The
size of the red blood cell is reduced
because less beta protein is made. If
inherited with the Hb S gene, you will
have Hemoglobin S Beta thalassemia.

Beta-Zero Thalassemia

Beta-Zero thalassemia is the second type
of beta thalassemia. It has similar
symptoms to Hb SS anemia. However,
sometimes the symptoms of beta-zero
thalassemia are more severe. It is
associated with a poorer prognosis.

People who only inherit a mutated gene
from only one parent are said to have
sickle cell trait. They may have no
symptoms or reduced symptoms.