Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of hemoglobin subunit delta and

hemoglobin subunit beta Hemoglobin subunit beta (beta globin, β-globin, haemoglobin beta, hemoglobin beta) is a globin protein, coded for by the ''HBB'' gene, which along with alpha globin ( HBA), makes up the most common form of haemoglobin in adult humans, hemogl ...

and raised levels of hemoglobin subunit gamma. It is an autosomal recessive disorder.

Signs and symptoms

An individual with delta-beta thalassemia is usually asymptomatic, however

microcytosis Microcytosis or microcythemia is a condition in which red blood cells are unusually small as measured by their mean corpuscular volume. When associated with anemia, it is known as microcytic anemia. Causes Microcytic anemia is not caused by re ...

can occur where the red blood cells are abnormally small.

Mechanism

Delta-beta thalassemia is autosomal recessive disorder, which means both parents are affected and two copies of the

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

must be present. 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. Delta-beta thalassemia is considered rare. 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. When two delta⁰ mutations are inherited, no

hemoglobin A2 Hemoglobin A2 (HbA2) is a normal variant of hemoglobin A that consists of two alpha and two delta chains (α2δ2) and is found at low levels in normal human blood. Hemoglobin A2 may be increased in beta thalassemia or in people who are heterozy ...

(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). The delta-beta thalassemia demonstrates one mutation is at the +69 position.

Relation to beta thalassemia

Delta-beta thalassemia can mask the diagnosis of

beta thalassemia Beta thalassemias (β thalassemias) are a group of inherited blood disorders. They are forms of thalassemia caused by reduced or absent synthesis of the beta chains of hemoglobin that result in variable outcomes ranging from severe anemia to cl ...

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

Diagnosis

Following the detection of

hypochromic Hypochromic anemia is a generic term for any type of anemia in which the red blood cells are paler than normal. (''Hypo''- refers to ''less'', and ''chromic'' means ''colour''.) A normal red blood cell has a biconcave disk shape and will have an a ...

microcytic

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s, delta-beta thalassemia is confirmed by

high-performance liquid chromatography High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...

Treatment

When needed, treatment for

anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...

, such as

blood transfusions Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mod ...

are used.

Stem cell transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...

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.

References

External links

{{Medicine Disorders of globin and globulin proteins Hereditary hemolytic anemias