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| {{Infobox Disease
| | #Redirect[[Thalassemia pathophysiology]] |
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| | ICD9 = {{ICD9|282.4}}
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| | MeshID = D055538
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| {{SI}}
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| ==Overview==
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| '''Delta-thalassemia''' is a form of [[thalassemia]]. It is associated with [[HBD]].<ref name="pmid9101295">{{cite journal |author=Drakoulakou O, Papapanagiotou E, Loutradi-Anagnostou A, Papadakis M |title=delta-Thalassemic phenotype due to two "novel" delta-globin gene mutations: CD11[GTC-->GGC (A8)-HbA2-Pylos] and CD 85[TTT-->TCT(F1)-HbA2-Etolia] |journal=Hum. Mutat. |volume=9 |issue=4 |pages=344–7 |year=1997 |pmid=9101295 |doi=10.1002/(SICI)1098-1004(1997)9:4<344::AID-HUMU7>3.0.CO;2-5 |url=http://dx.doi.org/10.1002/(SICI)1098-1004(1997)9:4<344::AID-HUMU7>3.0.CO;2-5}}</ref>
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| ==Pathophysiology==
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| As well as alpha and beta chains being present in hemoglobin about 3% of adult hemoglobin is made of alpha and delta chains. Just as with beta thalassemia, mutations can occur which affect the ability of this gene to produce delta chains.
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| * A mutation that prevents formation of any delta chains is termed a delta<sup>0</sup> mutation.
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| * One that decreases but does not eliminate production of delta chain is termed a delta<sup>+</sup> mutation.
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| When one inherits two delta<sup>0</sup> 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]], red cell distribution width). Individuals who inherit only one delta thalassemia mutation gene will have a decreased hemoglobin A2, but also no hematological consequences.
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| One mutation is at the +69 position.<ref name="pmid1309671">{{cite journal |author=Moi P, Loudianos G, Lavinha J, ''et al'' |title=Delta-thalassemia due to a mutation in an erythroid-specific binding protein sequence 3' to the delta-globin gene |journal=Blood |volume=79 |issue=2 |pages=512–6 |year=1992 |month=January |pmid=1309671 |doi= |url=http://www.bloodjournal.org/cgi/pmidlookup?view=long&pmid=1309671}}</ref>
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| ==Relationship to beta thalassemia==
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| The importance of recognizing the existence of delta thalassemia is seen best in cases where it may mask the diagnosis of [[beta thalassemia]] trait. In beta thalassemia, there is an increase in hemoglobin A2, typically in the range of 4-6% (normal is 2-3%). However, the co-existence of a delta thalassemia mutation will decrease the value of the hemoglobin A2 into the normal range, thereby obscuring the diagnosis of beta thalassemia trait.<ref name="pmid16434382">{{cite journal |author=Bouva MJ, Harteveld CL, van Delft P, Giordano PC |title=Known and new delta globin gene mutations and their diagnostic significance |journal=Haematologica |volume=91 |issue=1 |pages=129–32 |year=2006 |month=January |pmid=16434382 |doi= |url=http://www.haematologica.org/cgi/pmidlookup?view=long&pmid=16434382}}</ref> This can be important in genetic counseling, because a child who is the product of parents each of whom has beta<sup>0</sup> thalassemia trait has a one in four chance of having beta thalassemia major.
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| ==References==
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| {{reflist|2}}
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| {{Myeloid hematologic disease}}
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| [[Category:Genetic disorders]]
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| [[Category:Blood disorders]]
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