Thalassemia is an inherited blood disorder, the person has fewer red blood cells than a normal person. Therefore, the amount of oxygen-carrying protein is less in the body. Tiredness is most common and along with weakness, paleness, and slow growth.
Red blood cells carry oxygen. Oxygen is required for the cells to function properly in our body. When hemoglobin protein is not functioning well enough like a normal person, the person will not have enough red blood cells to make other cells functioning. Fewer red blood cells on the body and hence the person will feel tired, weak, or short of breath.
Mainly thalassemia occurred in Mediterranean and Southeast Asian populations.
- Caused by mutations in the alpha-globin genes (HBA1 and HBA2).
- Deletion of either HBA2 or HBA1 or both.
- Located on Chromosome 16 (16p13.3).
- HBA1 gene is responsible for transporting of oxygen from lung to various peripheral tissues.
- Alpha thalassemia trait is when someone has only two out of the normal four alpha-globin genes. In some people, they lead to no symptoms.
Predicted Human Phenotypes Of HEBA1:
- Malformation of biosynthesis pathway of heme.
- Hypochromic anemia. This means when the red blood cells are analyzed under the microscope, the red blood cells have less color.
- Hemoglobin abnormal.
- Microcytic anemia.
Summary of Research articles on alpha-thalassemia:
The intensity of disease is classified in to 2 section:
(1) alpha+ – caused by deletion or non-function of one of the four normal alpha globin genes.
(2) alpha0 – caused by deletion or non-function of two of the four normal alpha globin genes.
Clinical classification of Alpha-thalassemia is as follows:
Silent Carrier – hematologically & clinically normal.
Thalassemia trait – mild anemia, under the diagnosis of microscope red blood cells have less color.
HbH disease – Moderate to severe hemolytic anemia, mild jundice. Often consider as a mild disorder.
Hb Bart hydrops fetalis syndrome – Severe anemia, skeletal and cardiovascular malformation.
Reference – https://www.nature.com/articles/gim9201117
(2) Summary of Research Article – alpha thalassaemia allelle frequency in northern Thailand.
First highest allele frequency of alpha+ thalassaemia among Sino-Tibetan group.
Second highest allele frequency of alpha+ thalassaemia among Tai-Kadai group.
Third highest allele frequency of alpha+ thalassaemia among Austro-Asiatic group.
First highest allele frequency in Tai-Kadai group.
Second highest allele frequency in Austro-Asiatic group.
No allele frequency was observed in the Sino-Tibetan group.
The population in Northern Thailand consists of various ethnic group. However, they are divided into linguistic groups. (1) Present day population of northern Thailand consists of Tai-Kadai group.
(2) Austro-Asiatic group inhabit in remote areas and hill tribes. They are the decedents of prehistoric inhabitants of northern Thailand.
Beta-thalassemia is caused by mutations in the HBB gene (Hemoglobin Subunit Beta).
Beta-thalassemia is inherited in an autosomal recessive, which means both parents of HBB genes are mutated.
3 Types of clinical classification of beta-thalassemia.
(1) thalassemia major – transfusion dependent.
(2) thalassemia intermediate – intermediate severity.
(3) thalassemia minor – asymptomatic, carrier state.
Phenotype of Beta-Thalassemia:
(2) Microcytic anemia (small red blood cells)
(3) Abnormal hemoglobin
(4) Enlargement of spleen (splenomegaly)