Hgbopathies
Terms
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- Hgbopathies
-
-abn hgb structure usually pt.mutations
-mutations affect heme binding pocket =methemoglobin
-mutant hgbs have abn low o2 affinity =cyanosis
-some inc o2 affinity=polcythemia
-some muts have dec solubility=sickling - Thalessemia
-
-underprod of alpha or beta chains
Types:
alpha->dec alpha prod
beta->dec beta prod
minor->heterozyg
major->homozyg
occurs in: med,africa,mid east, southeast and south asia - Symptoms
-
-hypochromic microcytic anemia
-hemolysis
-anisocytosis(unequal size)
-poikilocytosis(weird shape)
-immature RBC's - Alpha thalassemia
-
-1 alpha gene del off of 1 chrome=>silent carrier b/c have 3 nrm genes=asymptomatic
-2 alpha genes del off of 2 diff chromos=>alpha thal minor=very mild symptoms
-2 alpha genes del off of same chromo=>alpha thal minor=very mild symptoms
-3genes del=>Hgb H disease=moderately severe anemia
-all 4 genes del=>barts,hydropsfetalis - Beta Thalassemia
-
-no beta chains=>beta0
-few beta chains=>beta+
-beta thal minor=>mild anemia,inc HbA2 and sometimes HbF
-beta thal intermedia=>b/t major and minor forms
beta thal major:
-severe anemia not at birth,
-abortive epoesis
-inc bone marrow
-chipmunck face
-abn skullxr
-hepatosplenomegally
-inc Fe absorption
-pigment stones - Tx for beta thal major
-
-spleenectomy
-repeated transfusions
-dessferrioxamine
-folic acid
-azacytidine
-BM transplantation - Sickle cell
-
-pt. mut of Glu->Val in position 6 of the beta chain (HbS)
-norm 02 affinity but dec in solubility of deoxy HbS (hydrophobic)
-cells sickle in venous bld only
-occurs in africa,mid east,india
-inheritence is AR
-carriers have improved resistance to malaria - Symptoms of sickle cell
-
no symps at birth
-hemolytic anemia
-mild jaundice
-painful crisis
-spleen/kidny infarctions
-ulcers
-spleenic sequestration crisis (kids)
-cerebrovascular accidents - Dx and TX
-
Dx:
-bld smear
-hgb electrophoresis
-DNA probes
Tx:
-iv fluids
-avoid hypoxia (exercise)
-drugs to inc gamma chain synth
-drugs to inc o2 affinity for sickle cells - Modifying traits
-
-HbF level
-Thalassemia trait
-HbC:
Glu->Lys subst. in position 6 of beta chain