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
SpecialtyHematology 
CausesProduces only gamma-globin and forms HbF(deletes entire delta and beta gene sequence)[1]
Diagnostic methodHigh-performance liquid chromatography
TreatmentBlood 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). 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

References
  1. "Delta-beta-thalassemia". Orphanet. Orphanet. Retrieved 16 September 2016.
  2. "Thalassaemia | Health | Patient". Patient. Retrieved 17 September 2016.
  3. "HBD - hemoglobin subunit delta". Orphanet. Orphanet. Retrieved 17 September 2016.
  4. Pal, G. K. & (2005). Textbook Of Practical Physiology - 2Nd Edn. Orient Blackswan. p. 53. ISBN 9788125029045. Retrieved 17 September 2016.
  5. "Autosomal recessive: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 17 September 2016.
  6. "Delta beta thalassemia carrier" (PDF). Public Health England. Public Health England. Archived from the original (PDF) on 24 September 2016. Retrieved 17 September 2016.
  7. "Transcription and Translation - National Human Genome Research Institute (NHGRI)". www.genome.gov. NIH. Retrieved 17 September 2016.
  8. Proytcheva, Maria, ed. (2010). Diagnostic pediatric hematopathology. Cambridge: Cambridge University Press. p. 61. ISBN 9780521881609. Retrieved 17 September 2016.
  9. "OMIM Entry - * 142000 - HEMOGLOBIN--DELTA LOCUS; HBD". www.omim.org. Retrieved 17 September 2016.
  10. 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.
  11. Ahmad SQ, Zafar SI, Malik HS, Ahmed S (November 2017). "Delta-Beta Thalassaemia in a Pathan Family". Journal of the College of Physicians and Surgeons (Pakistan). 27 (11): 722–724. PMID 29132487.
  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
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