Delta-beta thalassemia

Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of hemoglobin subunit delta and hemoglobin subunit beta and raised levels of hemoglobin subunit gamma. It is an autosomal recessive disorder.^[1][3]

Delta-beta thalassemia
Delta-beta thalassemia
Specialty	Hematology
Causes	Produces only gamma-globin and forms HbF(deletes entire delta and beta gene sequence)[1]
Diagnostic method	High-performance liquid chromatography
Treatment	Blood transfusions[2]

Signs and symptoms

An individual with delta-beta thalassemia is usually asymptomatic, however microcytosis can occur where the red blood cells are abnormally small.^[1][4]

Mechanism

Structure of hemoglobin the proteins α and β subunits are in red and blue,

Delta-beta thalassemia is autosomal recessive disorder,^[1] which means both parents are affected and two copies of the gene must be present.^[5] A carrier gets a normal gene to produce hemoglobin A, from one parent and the other parent supplies a gene which makes no hemoglobin A.^[6] Delta-beta thalassemia is considered rare.^[2]

Delta-beta-thalassemia is caused by deletions of the entire delta and beta genes sequences and only gamma-globin and HbF are formed. Rarely, non-deletional forms have been reported.^[7][8]

When two delta⁰ mutations are inherited, no hemoglobin A2 (alpha2, delta2) are formed. This is innocuous because only 2-3% of normal adult hemoglobin is hemoglobin A2. The individual will have normal hematological parameters (erythrocyte count, total hemoglobin, mean corpuscular volume).^{[medical citation needed]} The delta-beta thalassemia demonstrates one mutation is at the +69 position.^[9]

Relation to beta thalassemia

Delta-beta thalassemia can mask the diagnosis of beta thalassemia trait. In beta thalassemia, an increase in hemoglobin A2 results, but the co-existence of a delta-beta thalassemia mutation will decrease the value of the hemoglobin A2 into the normal range, thereby obscuring the diagnosis of beta thalassemia trait^[10]

Diagnosis

Following the detection of hypochromic microcytic red blood cells, delta-beta thalassemia is confirmed by high-performance liquid chromatography.^[11]

Treatment

When needed, treatment for anemia, such as blood transfusions are used.^[2]

Stem cell transplant is another option, but the donor and the individual who will receive the bone marrow transplant must be compatible, the risks involved should be evaluated.^[2][12][13]

See also

• Alpha thalassemia
• Beta-thalassemia
• Hemoglobinopathy