What is Beta Thalassaemia Minor for Family Physician Final

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What Should One Know About Thalassaemia Minor 

WhatIsThalassaemia?

§

  Thalassaemiaisacommoninheritedgeneticdisorderofhemoglobin(Hb).§  TounderstandThalassaemiaoneshouldknowabitmoreaboutHbanditsStructure&function.

UnderstandingBLOOD&ItsComponents?

§  TheOxygenfromlungiscarriedtotissuesbyamoleculecalledHemoglobin

§  HemoglobinispackedinRedCells.

§  BesidesRedcells(RBC)ourBloodalsocontainsWhitebloodcells(WBC)andPlatelets.§  TheWBCsareourdefensecellsandtheyhelpusfightinfections.

§  Platelets:aretinycellsthathelpclotbloodalongwithothercoagulationfactors.

§  TheliquidportionofBloodiscalledplasma.

WhatIsHemoglobin?

§  Hemoglobin(Hb)ispinkredincolor&itcarriesOxygenfromlungstotissues.

§  RBClifeis120daysandourBoneMarrowdailyproduces>200billionRBCstoreplace0.8%of

Bloodlostdaily.

§  TounderstandthenatureofdefectinthalassaemiaonehastounderstandthestructureofHB.

TellUsAboutStructureOfHemoglobin?

§  ThestructureofHBresemblesatransportvehicle.

§  HemeformsthecentreofHb&isverysimilartothechassisofavehicle;

§  Thefront&backwheelsareproteinattachmentscalledalpha&Betachain(Seefig1).

§  All components aremanufactured by genes at different sites and finallyassembled to form

completeHbmoleculeseefig1.

HowIsHemoglobinManufacturedInOurBody?

§  αchain,βchainandhemearemanufacturedatdifferentsitesintheerythroidcellsandfinally

assembledintoacompleteHBmolecule.

§  Foralphachainswehave4genes (αα /αα )seefig1.

§  Whileforbetageneswehave2genes (β/β)seefig1.§  Halfofthesegeneswereceivefromourmotherandhalffromfatherasshownin fig1.

WhatIsTheDefectInThalassaemia?

§  Thalassaemiaisbasicallyaquantitativedefectofthesechains.§  Thosewithan α chaindefectsarecalledα Thalassaemia.

§  Thosewithβ chaindefectsarecalledβ Thalassaemia.

WhatistheGeneticofThalassaemia?

§  Thalassaemiaisageneticdefectacquiredatbirth.

§  Oneisbornwithitandwillcarrythisdefectthroughoutone’slife.

§  Youcanalsopassonthisdefecttoyourchildren

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(Fig.1)Hemoglobinmoleculesimplifiedstructure&inheritanceofalphaandbetachainof

hemoglobin.

WhatAreTheClinicalTypesOfThalassaemia?

§  ClinicaltypesofβThalassaemia:

o  βThalassaemiaMinor:milddefectinwhichoneoutoftwo βchaingeneisdefective.

i.e.onegoodgeneandonebadgene. (β/-)seefig2.n  βThalassaemiamajor:severedefectinwhichboththeβ chaingeneisdefective

(-/-)Bothβgenesdefective

ChildrenbornwithThalassaemiamajorneedslifelongbloodtransfusiontosurvive.

“Knowledge about thalassaemia is important to prevent the birth of a child with thalassaemiamajor.”

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Fig2:showthedefectinβThalassaemiaMinorwherethereisquantitativedefectinone βchain.

Fig3:showthedefectinβThalassaemiaMajorwherethereisquantitativedefectinboth βchains.

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WhatIsTheMagnitudeOfProblem?

§  ThalassaemiaminorisextremelycommoninIndiaandthesouthEastAsiancountriesandthe

Mediterraneancountries.

§  Therewouldbemorethan30millionscasesofthalassaemiaminorortraitsinourcountry.

§  Thalassaemia minor is more common among certain communities like Lohanas, Kutcchis,

Sindhis, Bhanushalis, Khojas, Jains, Neobuddhists, Bhatias, Punjabis, agarwals, Muslims,Bengalisandvarioustribalgroupsthoughalmostanybodycouldhavethisgeneticdefect.

§  Theprevalencerateofβ ThalassaemiaMinoramongcertaincommunitiesmayvaryfrom1%

to5%.

§  Everyyearmorethan10,000childrenwiththalassaemiamajorareborninourcountry.

ThalassaemiaMinorOrThalassaemiaCarrierHowDoWeIdentifyThem?

§  βThalassaemiaMinor isoftenasymptomatic.

§  βThalassaemiaMinormayberecognizedwhenthereisachildwiththalassaemiamajorborn

inthefamily.

§  βThalassaemiaminormaypresentwithmildrefractoryanemia(HBbetween9to11gm/dl)

§  Exaggerationofanemiaduringpregnancy.§  IntheCBCreportofanindividual;ifRBCcountis>5.0millionwithmildanemiaorifMCV/RBC

ratiois<11itfavorsβThalassaemiaMinor.

HowDoesOneDiagnoseβThalassaemiaMinor?

§  DoHBelectrophoresis.HbA2valueof>3.5confirm βThalassaemiaminor.

§  PreferablydoHbElectrophoresisbyHPLCforaccuratevaluesofHbA2

§  Inhigh-riskcommunitiesscreeningforβthalassaemiaminorisveryrewarding,especiallyinthe

marriageableagegroup.

WhatIsTheImplicationOfDiagnosisOfβThalassaemiaMinorForAnIndividual?

§  Anindividualwithβ ThalassaemiaminorhasmildanemiawithHbinrangeof9 to11gm/dl.Whichisoftenunrecognized

§  Thereisnoeffectonhislifespanorhisroutineactivity.

§  Anemiamaygetexaggeratedtemporarilyduringpregnancy.

§  Themostimportantimplicationisgenetic.

GeneticCounseling:

§  IfBothHusbandAndWifeAreThalassaemiaMinorThePossibilitiesAreShownInFig4.

o  Thereis25%ofhavingachildwithThalassaemiaMajor

o  25%chanceofchildbeingNormal

o  50%chanceofchildbeingThalassaemiaMinor

§  IfOneOfThePartnersIsThalassaemiaMinorAndOneOfThemIsNormalThePossibilities

AreShownInFig5.

o  50%chanceofchildbeingNormal.

o  50%chanceofChildhavingβThalassaemiaMinor.

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Fig4:PossibilitieswhenbothparentsarebThalassaemiaMinor

Fig5:PossibilitieswhenoneparentisNormal&otherparentis β ThalassaemiaMinor

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HowCanWePreventTheBirthOfChildWithThalassaemiaMajor?

§  If you are from one ofthe high-risk communities Test your self for thalassaemiaminor

beforemarriage.

§  If you have thalassaemia minor then test your spouse and other family members for

thalassaemiaminor.

§  IfbothHusbandandwifehavethalassaemiaminor,foreverypregnancy,theyshouldgofor

antenataldiagnosistofindoutwhetherthechildtobebornisnormal,minorormajor.Incase the test show the fetus to be thalassaemia major then a decision regarding

continuationofpregnancyhastobemade.§  TheseantenataltestsareavailableinvariouscentersinIndia

§  Detailsabouttheantenataldiagnosiscanbefoundat www.thalassaemia.org

ThalassaemiaMajor:

§  Everyyeartherearemorethan10,000childrenwiththalassaemiamajorborninIndia.

§  Indiahasmorethan100,000casesofthalassaemiamajor.

§  Children bornwithThalassaemiamajor as thename suggestshas amajor problemwith

defectsinboththeßgenes.

§  Most are symptomatic by the age of 1 to 2 yearswith severe anemia, liver and spleen

enlargementandbonychanges.

§  Theyneedlifelongbloodtransfusionfortheirsurvival.

§  Bloodtransfusionisrequiredonceevery3to4weekstoalwaysmaintainHBabove9to10.5

gm/dl.

§  Lifelong blood transfusion has its own problems like Tx reactions, transmission of viral

infectionslikeHIV,HbsAG,HCV,otherviruses;Ironoverload.

§  Everyunitoftransfusiongivesthechildapproximately200to250mgofelementaliron

§  Bodydonothaveanyeffectivemeansofexcretingironhenceironaccumulationoccursin

variousorgansofthebodylikeliver,heart,Testes,pancreas,joints,parathyroid,thyroid,

Skinresultingindamagetotheseorgans.

§  Deathgenerallyissecondarytoheartandorliverfailure.

§  To remove excess iron from the body these children need to take some form of iron

chelationwitheitherdesferalorKelferorAsunra,whichalsohasitsownproblem.§  Some children the need for blood transfusion increases dramatically due to hyper

functioningspleeninwhichcasesplenectomywillhelpthechild.

§  Thesechildrenneedpsychologicalsupportfromdoctor,familyandprofessionalhelpwhen

necessary.

§  Themediansurvivalofachildwiththalassaemiamajorinourcountryisapproximately15to

20years.

§  Thesurvivalrateisimprovingandinstancesofthalassaemiamajorchildrenhavingattained

adulthood,marriedandhavingtheirownchildrenareseenmorefrequently.

§  Hopeandpositiveattitudeisofgreathelp.

CanWeCureThalassaemiaMajor?

§  TheonlycurativetreatmentisBoneMarrowTransplantation(BMT).

§  BMTcostsapproximately8to10lakhsofrupeesandacompletelymatchedsiblingdonor

forBMstemcells.

§  Thereisnorisktothedonor

§  Alternativesourceforstemcellsisumbilicalcordblood.

§  ThesuccessratewithBMTincompletelymatchedsiblingdonorisalmost80%

§  Thesuccessratedecreaseswithadvancedliverdiseaseintherecipient,ifitisamatchedbut

unrelateddonor.

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AreThereAnyResearchTreatmentsAvailable?

§  ThereistremendousresearchinterestinGenetherapy.

§  Sincethalassaemiaoccursbecauseofadefectivegeneitispossibletoreplacethisabnormal

geneandthechildcanbecured.

§  Thisisthefuturetreatmentandexpectationsareveryhigh.

§  Genetherapyshouldbecomeavailablebynextdecade.

PointsToRemember;“ClinicalPearls”

§  Therearemorethan30millionthalassaemiaminorcarriersinIndia

§  Youcouldbeoneofthem.Itisnotataboo

§  DoatestforThalassaemiaminorevenifyouappeartobehealthyespeciallyifyoubelongto

high-riskcommunity.

§  Ifyouhavethalassaemiaminorcheckwhetheryourspouse/spousetobeisathalassaemia

minor.

§  Ifbothyouandyourspousehavethalassaemiaminor,doaprenataltestbychorionicvillous

samplingveryearlyinpregnancy.§  Ouraimshouldbetopreventthebirthofchildwiththalassaemiamajor

§  Spreadawarenessaboutthalassaemia.

§  ChildrenafflictedwithThalassaemiaMajorneedourcompassionandsupport.

§  AllDoctorshaveanobligationtoSocietytopickuptelltalesigns,whichsuggestpresence

of β Thalassaemia Minor on CBC report, like an RBC count > 5.0 million suggesting

ineffectiveerythropoiesis;&MCV/RBCRatio<11favoringthepossibilityofβThalassaemia

Minor.

Dr Mukesh M Desai. M.D  Prof. of Pediatric Hematology Oncology (DNB)Hon. Hematologist Oncologist & Immunologist.

Department of PHO.Division Chief, Immunology;B. J. Wadia Hospital for Children.

Honorary Consultant HematologistNanavati Hospital.Sir H N Hospital.Saifee Hospital. Asian Heart Institute

Rooms: 

Hematology & Immunology Cell.B1 Matru Ashish,Next to Balbharti School; SV Road,Kandivili west, Mumbai 400067.

Cell : +91 9820037087.Clinic : +91 22 28092927;

+91 22 28092917.

Email: [email protected] URL: http://sites.google.com/site/mmdesai007/