Heme II Unit #1.3

Thalaseemia

mutation in one or more globin gene that causes decreased/absent synthesis of hgb. Microcytic/hypochromic

Alpha Thalassemia

occurs on chromosome 16

Beta Thalaseemia

occurs on chromosome 11

Ratio of Imbalance

decreased or absent globin chains are needed to assemble stable tetramers, excess causes decreased hgb production, ineffective erythropoiesis and chronic hemolysis

Excess Alpha Chain

occurs in severe forms of beta thalassemia. precipitate inside the cell and cause RBC deformability

Excess Gamma Chain

seen in fetus/newborn. Causes Hb Bart

Hb Bart

excess gamma chain, causes too high O2 affinity

Excess Beta Chain

causes HbH and is unstable

HbH

four beta chains combined into one hgb molecule. Too high O2 affinity

Chronic Hemolysis Causes:

splenomegaly, functional hyposplenism, gallstones

Demand for RBC:

increases erythropoiesis, increases iron absorption, and extra-medullary erythropoiesis

Thalassemia CBC

microcytic, hypochromic. NRBC N/decreased, RDW N/increased

Thalassemia Wright Stain

target cells, polychrom, baso stip, NRBC

Thalassemia Supravital Stain

precipitated excess chain, increased retic

Beta thalassemia

HbA decreased. Increased HbF and HbA2

Alpha thalassemia

HbA decreased and HbF and HbA2 too (HbH and Hb Bart present)

4 Deleted alpha genes

hydrops fetalis

3 deleted alpha genes

HbH disease

2 deleted alpha genes

alpha thalassemia minor

1 deleted alpha gene

silent carrier

Hydrops Fetalis

0/4 genes. ya dead. severe microcytic, hypochromic. 80-90% Hb Bart and 10-20% Hb Portland

HbH Disease

1/4 genes. non-fatal. HbH 2-40% in adults and Bart 25% in neonates. Golf-ball appearance

Alpha Thalassemia Minor

2/4 genes. asymptomatic. 5-6% bart undetible after 3 months

Alpha Thalassemia Silent

3/4 genes. normal hb synthesis, asympotamic

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