8 - Thalassemias and Hemoglobinopathies Flashcards
what causes the clinical features of thalassemias?
excess of the correctly produced chain
difference between thalassemias and hemoglobinopathies
thalassemia - mutation affecting the balance of chains produced
hemoglobinopathy - mutation in structure of one of the chains
types of mutations that result in alpha vs beta thalassemias
alpha - gene deletions
beta - point mutations that affect RNA functionality
what type of hemoglobin builds up in alpha thalssemias?
Hb H - beta tetramer
which type of thalassemia is worse?
beta
where in the world are thalassemias common?
regions where malaria is/was endemic (mediterranean, arabia, southern/SE asia)
when do alpha and beta thalassemia present, respectively?
alpha - at birth, beta - at least 4 mo after birth
which alpha thalassemia is more severe - the african or the SE Asian type?
SE Asian - 2 deletions, african is only 1 deletion
dx of alpha thalassemia trait
mild anemia, slightly low Hb, hypochromic microcytic. basically just need to rule out iron deficiency
difference on CBC between alpha thalssemia and iron deficiency anemia
often see thrombocytosis in iron deficiency, but not in alpha thalassemia
PBS findings in alpha thalassemia
Golf ball RBCs - micro Heinz bodies from precipitated Hb H
Hemoglobin H disease
type of alpha thalassemia with 3 alleles affected where you get Hb Barts (tetramers of gamma) in addition to Hb H. can lead to more serious complications
Hemoglobin Constant Spring (CS)
Asian gene mutation, stop codon mutation that results in long unstable globin. Form of alpha thalassemia that is not due to a deletion
PBS findings for beta thalassemia minor
microcytic, hypochromic, lot of targeting, some basophilic stipling. More consistent in size than in iron deficiency anemia
pathophys of beta thalassemia
extra alpha globin > inc ROS > membrane damage
ineffective erythropoiesis leading to iron overload and anemia > inc EPO > extramedullary hematopoiesis
hemolysis
