Delta-beta thalassemia

Delta-beta thalassemia is a form of thalassemia, and is autosomal recessive in terms of heredity.[1] It is associated with hemoglobin subunit delta.[4]

Delta-beta thalassemia
Delta-beta thalassemia
SpecialtyHematology 
CausesProduces only gamma-globin and forms HbF(deletes entire delta and beta gene sequence)[1]
Diagnostic methodCBC[2]
TreatmentBlood transfusions[3]

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][5]

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

In regards to genetics, delta-beta thalassemia is autosomal recessive,[1] which means both parents (two copies of the gene) must be present.[6] 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.[7] Delta-beta thalassemia is considered rare.[3]

In terms of the pathophysiology of delta-beta thalassemia, one finds delta and beta chains have deletion, therefore gamma genes are what is transcribed (made an RNA copy of[8]) on the impaired chromosome.[9]

When one inherits two delta0 mutations, no hemoglobin A2 (alpha2, delta2) can be formed. Hematologically, however, 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.[10]

Relation to beta thalassemia

The importance of recognizing the existence of delta-beta thalassemia is seen best in cases where it may mask the diagnosis of beta thalassemia trait. In beta thalassemia, an increase in hemoglobin A2 results. However, 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[11]

Diagnosis

The diagnosis of delta-beta thalassemia is done via hypochromic microcytic red cell indices.[1] This test is a part of a CBC, and could be employed to diagnose the reason the individual might have anemia, in this case due to thalassemia.[2]

Treatment
BT for IV

In terms of treatment for delta-beta thalassemia one possible concern would be anemia, where, therefore, blood transfusions would be given to the affected individual (though blood transfusions might introduce complications, as well).[3]

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, as well[3][12][13]

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See also
  • Alpha thalassemia

References
  1. "Delta-beta-thalassemia". Orphanet. Orphanet. Retrieved 16 September 2016.
  2. "RBC indices: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 17 September 2016.
  3. "Thalassaemia | Health | Patient". Patient. Retrieved 17 September 2016.
  4. "HBD - hemoglobin subunit delta". Orphanet. Orphanet. Retrieved 17 September 2016.
  5. Pal, G. K. & (2005). Textbook Of Practical Physiology - 2Nd Edn. Orient Blackswan. p. 53. ISBN 9788125029045. Retrieved 17 September 2016.
  6. "Autosomal recessive: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 17 September 2016.
  7. "Delta beta thalassemia carrier" (PDF). Public Health England. Public Health England. Retrieved 17 September 2016.
  8. "Transcription and Translation - National Human Genome Research Institute (NHGRI)". www.genome.gov. NIH. Retrieved 17 September 2016.
  9. Proytcheva, edited by Maria (2010). Diagnostic pediatric hematopathology. Cambridge: Cambridge University Press. p. 61. ISBN 9780521881609. Retrieved 17 September 2016.CS1 maint: extra text: authors list (link)
  10. "OMIM Entry - * 142000 - HEMOGLOBIN--DELTA LOCUS; HBD". www.omim.org. Retrieved 17 September 2016.
  11. Galanello, Renzo; Origa, Raffaella (2010). "Beta-thalassemia". Orphanet Journal of Rare Diseases. 5 (1): 11. doi:10.1186/1750-1172-5-11. ISSN 1750-1172. PMC 2893117. PMID 20492708.
  12. Cao, Antonio; Galanello, Renzo (2010-02-01). "Beta-thalassemia". Genetics in Medicine. 12 (2): 61–76. doi:10.1097/GIM.0b013e3181cd68ed. ISSN 1098-3600. PMID 20098328.
  13. "Risks". nhs.uk. Retrieved 2018-04-28.

Further reading
Classification
External resources
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