Delta-beta thalassemia explained

Delta-beta thalassemia
Causes:	Produces only gamma-globin and forms HbF(deletes entire delta and beta gene sequence)
Diagnosis:	High-performance liquid chromatography
Treatment:	Blood transfusions

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] [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] [3]}

Mechanism

Delta-beta thalassemia is autosomal recessive disorder,^[1] which means both parents are affected and two copies of the gene must be present.^[4] 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.^[5] Delta-beta thalassemia is considered rare.^[6]

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.^[6]

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.^{[6] [12] [13]}

See also

• Alpha thalassemia
• Beta-thalassemia
• Hemoglobinopathy

Further reading

• Verma. S. Bhargava. M. Mittal. SK. Gupta. R. Homozygous delta-beta Thalassemia in a Child: a Rare Cause of Elevated Fetal Hemoglobin. Iranian Journal of Pediatric Hematology and Oncology. 1 January 2013. 3. 1. 222–227. 3915439. 2008-8892. 24575268.
• Kumar. B. Vinodh. Choccalingam. Chidambharam. Samuel. Premila. Incidental Identification of Possible Delta-Beta Thalassemia Trait in a Family: A Rare Cause of Elevated Hb F.. Journal of Clinical and Diagnostic Research. 1 March 2016. 10. 3. BD01–BD02. 10.7860/JCDR/2016/16352.7409. 4843246. 2249-782X. 27134860.
• Web site: Public Health Information Network Vocabulary Access and Distribution System (PHIN VADS). CDC. Centers for Disease Control. 17 September 2016.

Notes and References

1. Web site: Delta-beta-thalassemia. Orphanet. 16 September 2016.
2. Web site: HBD - hemoglobin subunit delta. Orphanet. 17 September 2016. 18 September 2016. https://web.archive.org/web/20160918085238/http://www.orpha.net/consor/cgi-bin/Disease_Genes.php?lng=EN&data_id=20551&MISSING%20CONTENT=hemoglobin-subunit-delta&search=Disease_Genes_Simple&title=hemoglobin-subunit-delta. dead.
3. Book: Pal. G. K. &. Textbook Of Practical Physiology - 2Nd Edn.. 2005. Orient Blackswan. 9788125029045. 53. 17 September 2016. en.
4. Web site: Autosomal recessive: MedlinePlus Medical Encyclopedia. medlineplus.gov. 17 September 2016.
5. Web site: Delta beta thalassemia carrier. Public Health England. 17 September 2016. 24 September 2016. https://web.archive.org/web/20160924163415/https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/540622/1746-delta_beta_thalassaemia-PRINT_250716.pdf. dead.
6. Web site: Thalassaemia Health Patient. Patient. 17 September 2016.
7. Web site: Transcription and Translation - National Human Genome Research Institute (NHGRI). www.genome.gov. NIH. 17 September 2016.
8. Book: Proytcheva. Maria. Diagnostic pediatric hematopathology. 2010. Cambridge University Press. Cambridge. 9780521881609. 61. 17 September 2016. en.
9. Web site: OMIM Entry - * 142000 - HEMOGLOBIN--DELTA LOCUS; HBD. www.omim.org. 17 September 2016.
10. Galanello. Renzo. Origa. Raffaella. Beta-thalassemia. Orphanet Journal of Rare Diseases. 2010. 5. 1. 11. 10.1186/1750-1172-5-11. 1750-1172. 20492708. 2893117 . free .
11. Ahmad SQ, Zafar SI, Malik HS, Ahmed S . Delta-Beta Thalassaemia in a Pathan Family . Journal of the College of Physicians and Surgeons (Pakistan) . 27 . 11 . 722–724 . November 2017 . 29132487 .
12. Cao. Antonio. Galanello. Renzo. 2010-02-01. Beta-thalassemia. Genetics in Medicine. en. 12. 2. 61–76. 10.1097/GIM.0b013e3181cd68ed. 20098328. 1098-3600. free.
13. Web site: Risks. nhs.uk. en-GB. 2018-04-28.