Alpha Thelesemia

Alpha Thalassemia

Prevalence

People whose hemoglobin does not produce enough alpha protein have alpha thalassemia. It is commonly found in Africa, the Middle East, India, Southeast Asia, Southern China, and occasionally the Mediterranean region.

There are four types of alpha thalassemia depending on the number of gene involved ranging from single gene deletion to all four gene deletion. The clinical scenario developed in the form of mild to severe form depending on the number of alpha gene deletion.

Silent Carrier State: This condition generally causes no health problems because the lack of alpha protein is so small that the hemoglobin functions normally. It is called “silent carrier” because of how difficult it is to detect. Silent carrier state is “diagnosed” by deduction when an apparently normal individual has a child with hemoglobin H disease or alpha thalassemia trait.

Hemoglobin Constant Spring: This is an unusual form of Silent Carrier state that is caused by a mutation of the alpha globin. It is called Constant Spring after the region of Jamaica in which it was discovered. As in silent carrier state, an individual with this condition usually experiences no related health problems.

Alpha Thalassemia Trait or Mild Alpha Thalassemia: In this condition, the lack of alpha protein is somewhat greater. Patients with this condition have smaller red blood cells and a mild anemia, although many patients do not experience symptoms. However, physicians often mistake mild alpha thalassemia for iron deficiency anemia and prescribe iron supplements that have no effect on the anemia.

Hemoglobin H Disease: In this condition, the lack of alpha protein is great enough to cause severe anemia and serious health problems such as an enlarged spleen, bone deformities and fatigue. It is named for the abnormal hemoglobin H (created by the remaining beta globin) that destroys red blood cells.

Hemoglobin H-Constant Spring: This condition is more severe than hemoglobin H disease. Individuals with this condition tend to have a more severe anemia and suffer more frequently from enlargement of the spleen and viral infections.

Homozygous Constant Spring: This condition is a variation of hemoglobin H-Constant Spring that occurs when two Constant Spring carriers pass their genes on to their child (as opposed to hemoglobin H Constant Spring, in which one parent is a Constant Spring Carrier and the other a carrier of alpha thalassemia trait). This condition is generally less severe than hemoglobin H Constant Spring and more similar to hemoglobin H disease.

Hydrops Fetalis or Alpha Thalassemia Major: In this condition, there are no alpha genes in the individual’s DNA, which causes the gamma goblins produced by the fetus to form abnormal hemoglobin called hemoglobin Barts. Most individuals with this condition die before or shortly after birth. In some extremely rare cases where the condition is discovered before birth, in utero blood transfusions have allowed the birth of children with hydrops fetalis who then require lifelong blood transfusions and medical care

Alpha Thalassemia Haematological Diagnostic tools

Complete Blood count

For affected individuals Complete Blood count usually shows significant anemia, microcytosis, hypochromic and abnormal red cell morphology.
1% Brilliant cresyl Blue

In HbH disease HbH inclusion bodies with 1% Brilliant cresyl Blue
Hb Electrophoresis

If HbH range between 5-30% it can be detected by Hb electrophoresis, IEF, HPLC.
Alpha beta Globin Chain synthesis ratio

Most direct approach and reports on the basis of alpha and beta globin chain ratio.
Molecular analysis

Following tools can be useful e.g Gap PCR, Reverse Dot Blot by Hybridization, Multiplex ARM PCR, and Southern Blotting.

Alpha Thalassemia Treatment

• Preventive & supportive
• Folic acid supplements if evidence of hemolysis.
• Avoid oxidative compounds medications.
• Avoid iron therapy unless iron deficiency documented and periodic monitoring of iron overload.
• Prompt treatment of infections.
• Splenomegaly: If marked splenomegaly consider pre splenectomy work up & splenectomy.
• Special attention for pregnant women with HbH.
• Risk of fetal neural tube defect. Folic acid supplements during periconceptual period and beyond.
• Iron supplements if iron deficient