People who do not produce enough alpha globin protein have alpha Thalassaemia. It is commonly found in Africa, the Middle East India, Southeast Asia, Southern china, and occasionally the Mediterranean region.
Alpha globin is made by four genes, two on each strand of the chromosome 16. Individuals who have one or two abnormal alpha globin genes have alpha Thalassaemia trait.
An individual with alpha Thalassaemia trait defined by the presence of one abnormal alpha globin gene is said to have the silent carrier state. This condition, in which one of the four alpha globin genes is missing or detective, generally causes no health problems because the lack of alpha globin protein is so small that there is no anemia.
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 Thalassaemia minor. It can also be diagnosed by special DNA testing.
An Individual with alpha Thalassaemia trait defined by the presence of two abnormal alpha globin genes is said to have Alpha Thalassaemia Minor.
Alpha Thalassaemia Minor
In this condition, in which two of the four alpha globin genes are missing or defective, the lack of alpha globin protein is somewhat greater. Patients with this condition have smaller red blood cells and a mild anemia, although they do not experience symptoms.
Physicians often mistake alpha Thalassaemia minor for iron deficiency anemia and prescribe iron supplements that have no effect on the anemia. Both abnormal alpha globin genes may be on the same chromosome (cis position) and one may be on each chromosome in the pair (transposition)