section 19 - thalessemias

Question 1

define thalassemia

Answer 1

decreased production of one or more globulin chains classified based on what chain is effected

Question 2

what chromosome codes for alpha family and beta family

Answer 2

• 16 alpha
• 11 beta

Question 3

describe beta thalassemia

Answer 3

beta chain production decreased affecting amt hgb A is made

Question 4

describe the main problem of beta thalassemia

Answer 4

uncoupling of alpha and beta chain production causing
- excess free alpha chain
- decreased total hgb

Question 5

how does free alpha chain result in lysis

Answer 5

free alpha chains are unstable and denature to form precipitates that cause RBC destruction in marrow

Question 6

list genetic designations of beta thal

Answer 6

• beta: normal
• beta 0: zero beta chains
• beta +: some beta production but still low
• beta ++s: produce >50% beta chains -> silent carrier

Question 7

describe characteristics of silent carrier beta thal

Answer 7

only a small decrease in beta chain production with no hematological abnormalities

Question 8

describe characteristics of beta thal minor

Answer 8

• mild to mod anemia
• decreased osmo fragility
• BM erythroid hyperplasia
• hgb A2 inc
• hgb F inc

Question 9

describe characteristics of beta thal major

Answer 9

• marked bone changes due to expanded marrow
• hemolysis due to inc free alpha chains
• extramedullary hematopoiesis
• serum iron and ferritin inc

Question 10

complications of beta thal major

Answer 10

• iron overload due to transfusions
• grave prognosis

Question 11

describe beta thal major treatment

Answer 11

• regular blood transfusions
• iron chelation therapy
• remove spleen if necessary

Question 12

describe delta beta thal

Answer 12

neither hgb A or hgb A2 produced in normal quantities

Question 13

describe hereditary persistence of fetal hemoglobin (HPFH)

Answer 13

continued synthesis of high lvls hgb F in adult life with absence of clinical/hematological thal findings

Question 14

list other beta chain family defects

Answer 14

• hgb E (beta chain defect with diminshed production)
• hgb lepore (delta beta fusionwith diminished production)

Question 15

how many alpha chain genes does the child get from parents

Answer 15

2 from each for a total of four alpha chain coding regions

Question 16

describe silent carrier for alpha thal

Answer 16

only one out of four genes defective
- asymptomatic

Question 17

describe alpha thal minor

Answer 17

• 2 of four genes defective
• mild micro hypo anemia
• decreased osmo fragility
• BM erythroid hyperplasia

Question 18

describe hgb H disease

Answer 18

• alpha thal with 3 of 4 genes defective
• free beta family chains

Question 19

list the two kinds of tetramers free beta family chains can form

Answer 19

• gamma 4 tetramer = hgb barts
• beta 4 tetramer = hgb H forms heinz bodies

Question 20

what stain is used to determine hgb H inclusions

Answer 20

supravital - will look like golf ball

Question 21

what beta family tetramer is in high levels in hydrops fetalis

Answer 21

• defect in all 4 alpha chains
• high levels of hgb barts (gamma)

Question 22

describe alpha thal treatment

Answer 22

• regular blood transfusions
• iron chelation therapy
  daily folic acid

Question 23

describe hgb constant spring

Answer 23

alpha chain defect with diminished production

Question 24

list thalassemia lab findings (generally)

Answer 24

• osmotic fragility decrease due to target cells
• supravital stain pos for heinz bodies due to unstable tetramers
• hgb electrophoresis for beta thal diagnosis