Thalassemia Flashcards
Chromosome affected in thalassemia major
Chr. 11
Hb Electrophoresis results in a newborn (Day 0) vs adults (or 6 mnths old baby)
DAY 0 Adult (or 6mnths)
HbF: 95% HbF: 2%
HbA: 2% HbA: 95%
HbA2: 3% HbA2: 3%
First Hb to develop in a fetus
Gower 1, followed by Gower 2, followed by Portland
Sited of hematopoiesis @2wks, 14wks & 38wks.
2wks.: Yolk sac (Gower 1)
14 wks.: Liver, spleen (HbF)
38 wks.: Bone marrow (HbA starts appearing)
Most common site of hematopoiesis in newborn (Day 0)
Skull>Vertebra>Sternum>Ribs>Clavicle>Long bones>Flat bones (basically, all bones)
Most common site of hematopoiesis after 18yrs of age
Flat bones
Hallmark feature of all hemolytic anemias? Exception?
Hallmark feature: Splenomegaly
Exception: Sickle cell anemia
Kind of defect present in Thalassemia Major
(Alpha2, Aplha2) i.e., Alpha4 tetramers
Normal: Alpha2, Beta2
Reason for ineffective erythropoiesis
Most of the defective RBC produced die within the BM itself, while the remaining die in the spleen. So the BM is doing the necessary work to produce RBCs but its of no use as the ones produced are defective.
Reticulocyte levels in hemolytic anemias? Exception?
Reticulocytosis seen in hemolytic anemias
Exception: Thalassemia Major (reticulocytopenia)
Clinical features of px with thalassemia major
- Young kid
- Severe anemia (Pallor) w/ CHF (excessive sweating on
breastfeeding, lethargy, pulm. edema, dyspnea) - Splenomegaly
- Frontal/Maxillary prominence (d/t BM expansion) — Chipmunk facies
- Extramedullary hematopoiesis: Splenohepatomegaly (spleen more enlarged than liver cuz spleen doing double duty, of hematopoiesis, as well as destruction of defective RBCs)
Chipmunk Facies - Prominent cheek bones, prominent frontal & maxillary bones, upturned nostrils (upward facing nostrils)
% of Beta chain production in different types of beta thalassemia
Thalassemia Major: (Beta0, Beta0) - 0% production
Thalassemia Intermedia: (Beta0, Beta+) - 50% production
Thalassemia Minor: (Beta+, Beta+) - 90% production
(asymptomatic, incidental dx - dec. Hb)
Severity: Major>Intermedia>Minor
Screening test for thalassemia
NESTROFT (Naked Eye Single Tube RBC Osmotic Fragility Test)
- Osmotic fragility: DEC. IN THALASSEMIA
INC. IN HEREDITARY SPHEROCYTOSIS
IOC for thalassemia
HPLC (High Performance Liquid Chromatography) > Hemoglobin electrophoresis
- Hb Electrophoresis: If HbA2 > 3%, indicates thalassemia
Prenatal dx. for thalassemia
- Chorionic villi sampling @ 10-12 wks. AOG
- Amniocentesis or Chordocentesis if mother presents @
2nd trimester