Definition Disorder involvi ng the Rate of Globin Synthesis ↓ or Absent synthesis of 1≥ Globin type β Thalassaemia - ↓ β chain synthesis α Thalassaemia - ↓ α chain synthesis synthesis Haemoglobinopathy Globin structure is abnormal (Qualitat (Qualitat ive) Am ino Acid Substitution Substit ution in Globin Chain HbS HbC Heterogenous group of Genetic disorders
Hb A (α2β2) 96-98%
Hb A2 (α2δ2) 3.5%
Hb F ( α2 α2γ ) <1%
Divided into α, β, δβ, γδβ Thalassaemia Inherited in Mendelian Rec Recessive essive fashion Classification/ Nomen Nomen clature Clinical Clinical Hydrops Fetalis – Intrauterine death
Synthesis Globin
Thalassaemia Major (Transfusion dependant) Thalassaemia Intermedia (Splenomegaly) Thalassaemia Minor (Symptomless)
Haemogobin Abnormali Abnormali ties ↓ Rate of Synthesis of Normal Globin chain Synthesis of Abnormal of Abnormal Haemoglobin
Genetic
α Thalassaemia
β Thalassaemia
Definition ↓ Production of α chains Commonly Commonly due to Gene(s) Deletion
Definition Commonly with Point Mutations (Uncommon (Uncommon wit h Deletions) 3 Clinical Phenotypes Minor/ Carrier Intermedia Severe/ Major
Terminology chromosome is inactiv ated α - 1 gene on 1 chromosome α - Both genes on 1 chromosome are inactivated Classification of α Thalassaemia (No (No α Thalassaemia Major) Normal Minor Hb H Disease Barts Hydrops Hydrops Fetalis αα /αα
-α/αα -α/-α --/αα
Normal
Terminology β - No Production at all β - ↓ Amount of Production of β Chain
Classification & Term inology inology β Thalassaemia
--/-α --/α
--/--/--
Normal β/β
Minor β/β β/β
Intermedia β /β Clinically can be Minor/ Major
Hb H Disease
Hydrops Hydrops Fetalis
Pathophysiology Pathophysiology of β Thalassaemia
Major β /β β /β
Trait Hydrops Hydrops Fetal is
Trait Pathophysiology Pathophysiology Imbalance of Globin Genes Normal Normal α /β chain chain ra tio = 1:1 Ratio is ↓ in α Thalassaemia Thalassaemia Excess of chain (Lead (Lead to Precipitation) β4 – HbH γ4 – Hb Bart’s HbH Inclusions can be demonstrated in Red Cells (↓ in Trait) (↑ in Intermedia/ HbH Disease) Clinical Clinical F eatures Thalassaemia Trait In 1 & 2 Genes Deletion Asymptomatic Asy mptomatic Only Mil d/ No Anaemia Hypochromic, Microcytic Red Cells TRBC count ↑ (5.5x 10/L) Normal Normal Hb Electrophoresis
Investigations Screening FBC/ FBP Osmotic Osmotic Fra gilit y Test HbH Inclusion Body Hb Electrophoresis Electrophoresis HPLC
ζ Chain Analysis Confirmatory DNA Analaysia
Clinical Clinical Phenotypes of β Thalassaemia
Hb H Disease
Hydrops Hydrops Foetalis
Thalassemia Intermedia with 3 genes Deletion
4 Genes Deletion Incompati Incompati ble for Life Hb Bart (Hb Bart disease)
Hb rang e – 7-11 g/dL Intermittent Haemolytic Haemolytic episodes after Infection, Pregnancy
Thalassaemia Major (Cooley’s anaemia)
Thalassaemia Intermedia
Thalassaemia Trait
Profound Profound Anaemia
Moderate → Severe Anaemia
Clinically Asymptomatic
Total Transfusion Transfusion Dependence
Occasion Occasional al Transfusio Transfusio n Required
Very Mild → No Anaemia Hypochromic Microcytic Red Blood Cells
Splenomegaly Hb H on El ectrophoresis ectrophoresis H Inclusions detected on Blood Film
Investigation Screening
Management Blood Transf usi on
FBC/ FBP Osmotic Osmotic Fra gilit y Test Hb El ectrophoresis ectrophoresis
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Evidence of Impaired Growth & Development during growth Spruts
Treatment No Treatment – since they are Asymptomatic Asymptomatic Hb H is treated tre ated only only when patient pati ent is Symptomatic (Haemolytic Episodes) by Transfusion, Transfusion, Avoiding Dr ugs
Blood Transfusion regime starts Evidence of Iron Overload Therapeutic augmentation of Hb F Production Production
Hydrops Foetalis is Incompatible Incompatible for for Life Life Prevention by Parental, Prenatal Prenatal screening of Foetus, Genetic Counselling
Non-Deletional Non-Deletional α Thalassaemia ( ) Uncommon Pathogenesis Point Mutation Mutation a ffecting ffecting Termination of Translat ion Hb Constant spring (most common) Blood Smear/ Hb H Preparation
Hepato-splenomegaly FBP Target Cells Hypochromic, Hypochromic, M icrocytic Thalassaemia Peripheral Peripheral Blood F ilm HbH Inclusion Body Golf Ball A ppearance
Frontal Bone Enlarged Hair-on-End Appearance
Haemoglobinopathy Thalassemia Trait
Hb S Disease/ Sickle Cell (S S) Disease Mutation in β globin gen Heterozygous (β/β) – Asymptomatic Asymptomatic// Mild A naemia / No Anaemia (Normal (Normal Red Cells, Occ. Haemolytic Crisis/ S ickling during Anaesthesia) Anaesthesia) Homozygous ( β/β) – More Severe presentation (Haemolysis & Punctuated by crisis) Laboratory Hb ↓ Sickle cells i n Blood Splenic Atrophy Pathophysiology Pathophysiology
Hypochromic, Microcytic Target Cells Thalassemia Major Clinical Asymptomatic at Birth st Symptoms appear appear a s % of Feta l Hb ↓during ↓during 1 year of Life Untreated crises ↑ Morbidity & Early Death Clinical Clinical F eatures Complications Haemolysis Folate Deficiency Deficiency Occlusion of blood vessels Aplastic Crisis Renal Papillary Necrosis • Bone (Painful Crisis) Infection Infection (Pneumo (Pneumo coccal) • Lung (Acute Chest Syndrome) Leg ulcer • Brain Priapism • Heart
• •
Nucleated RBC Fragment β Thalassemia Thalassemia Major (Post Splenectomy) Splenectomy)
Spleen (Acute Splenic Sequestration)
Hands (Dactylit (Dactylit is in Children) Therapy Symptomatic – Painful Crisis Hydroxyurea – Painful Crisis Transfusions Transfusions – Sev ere Anaemia Exchange Transfusion - CNS events, Chest Syndrome Folate Prophylaxis Allogeneic Mar row Transplantation Transplantation Sickle Cell Trait Heterozygous Stage for HbS (HbAS) No serious clinical consequences Sudden death during intensive training Haematuria (Renal (Renal Papill ary Necrosis) Blood Film
Hb E Disease Mutation in β globin gene (comm (common on in SEA – inc. Malay sia) Types Hb E Trait (β/β) – Mild Anaemia/ Asymptomatic Hb E Disease/ Homozygous Hb E ( β/β) – Mild Anaemia/ Asymptomatic Compound Com pound Heter ozygous ( β /β or β /β) – Resemble Thala ssemia ssemia Intermedia or Homozygous β Thalassemia, Become Transfusion Dependant
Hb Electrophoresis
HPLC
Principle At A lkali ne pH (8.4-8.6) (8.4-8.6) – Hb is –ve charged protein When placed in electrical field, Hb migrates towards anode (+)
Principle Fully Automated Analyzer Cation exchange exchange Hi gh Performance Performance l iquid c hromatogra hromatogra phy
Separat ion of Hb fraction of agarose gel (based (based on Electrophoretic mobility mobility )
Separat e & Determine Determine Area % for HbA2, HbF Provide Qualitat ive determinations of Abnormal Hb by identification of Peaks, Retention time Analyte F P2 P3 A0 A2
Hb A Hb A2 HbF
96-98% 3.5% <1%
(Memorize - Hb A2 ↑ but not more than 8%)
Lane 1 Hb A 90% Hb A2/E 8% Hb F 2% β Thalassemia (Minor)
Lane 4 Hb A 77.2% Hb A2/E 2.8% Hb F 1.0% HbH 12% Hb Bart 7% α Thalassemia
Lane 6 Hb A 70% Hb A2/E 29% Hb F 1% Hb E Trait (β/β) Lane 3 Hb A 0% Hb A2/E 98% Hb F 2% Hb E Disease Lane 3 Hb A 4.1% Hb A2/E 58.2% Hb F 37.7% Compound Hb E β Thalassemia β /β
