Haemoglobinopathies

Question 1

what chromosome are alpha genes found on?

Answer 1

16

(2 per chromosome)

Question 2

what chromsome are beta genes found on?

Answer 2

11

(1 per chromosome)

Question 3

at what age are adult levels of Hb achieved?

Answer 3

6-12 months

Question 4

how can haemoglobinopathies interfere with HbA1c?

Answer 4

they can give falsely low HbA1c as shorten the life span of RBC

Question 5

conditions affecting globin chain synthesis are usually what pattern of inheritance?

Answer 5

autosomal recessive

Question 6

what is thalassaemia?

Answer 6

decreased rate of globin chain synthesis

Question 7

why are unbound globin chains dangerous?

Answer 7

they are toxic and result in haemolysis

Question 8

inadequate Hb production in thalassaemia will lead to what kind of anaemia?

Answer 8

microcytic hypochromic anaemia

Question 9

in alpha thaassaemia how many genes are lost in

1) alpha 0
2) alpha +

Answer 9

1) 2/4 genes lost
2) 1/4 genes lost

Question 10

what is the severe form of alpha thalassaemia called?

Answer 10

HbH disease- 1 gene per cell

Question 11

how is HbH formed in HbH disease?

Answer 11

excess B chains form tetramers called HbH which can’t carry oxygen

Question 12

what symtpoms are seen in HbH disease?

Answer 12

jaundice due to haemolysis

inefective erythropoiesis

splenomegaly

Question 13

what is the severst form of alpha thalassaemia?

Answer 13

Hb Barts hydrops fetalis syndrome

Question 14

how many alpha genes are inherited in Hb Barts?

Answer 14

no alpha genes inherited from either parent- cannot make HbA

Question 15

what kind of Hb is made in Hb Barts?

Answer 15

HbF- four gamma chains, extremely high affintiy fro oxygen to hardly any delivery to tissues

Question 16

what kind of mutation usually causes disorder of beta chain synthesis in beta thalassaemia?

Answer 16

point mutation

Question 17

does beta thalassaemia affect HbA and HbF?

Answer 17

no- only afects adult haemoglobin not foetal

Question 18

how is beta thalassaemia intermedia treated?

Answer 18

occasional transfusion

(moderate severity)

Question 19

when does beta thalassaemia major present?

Answer 19

6-24 months (as HbF falls)

Question 20

what is the management of beta thalassaemia major?

Answer 20

regular transfusion to maintain Hb

Question 21

what is the main concern with regular transfusions in beta thalassaemia major?

Answer 21

iron overload

Question 22

if you suspect a thalassaemia what else should you check first to rule out anaemia?

Answer 22

ferritin

Question 23

what are chelating drugs?

Answer 23

bind to iron formign complexes that can then be excreted in urien or stool

Question 24

what is an example of a chelating drug used in iron overload?

Answer 24

desferrioxamine

Question 25

in sickling disorders what gene suffers a point mutation?

Answer 25

B globin gene

Question 26

what is glutamine substituted to in sickling disorders?

Answer 26

valine

Question 27

what is the genotype of someone with sickle cell trait?

Answer 27

one abnormal, one normal gene

Question 28

is sickle cell trait symtpomatic?

Answer 28

No- asymtpomatic in carrier state

Question 29

what inheritance is sickle cell anaemia?

Answer 29

autosomal recessive

Question 30

what would appear on teh blood film of somone with sickle cell anaemia?

Answer 30

sickle red cells as all HbS and no HbA

Question 31

what can occur in sickle cell anaemia?

Answer 31

sickle crisis

chronic hameolysis

hyposplenism

Question 32

what is sickle crisis?

Answer 32

tissue infarction due to distorted sickle cells occluding vessles- causes ischaemia and pain

Question 33

why do people with sickle cell anaemia suffer hyposplenism?

Answer 33

due to repeated splenic infarcts

Question 34

what is the treatment of Sickle Crisis?

Answer 34

strong analgesia

IV/fluids hydration

oxygen

treat any infection

red cell exchange in severe crisis

Question 35

what are the long term effects of sickle cell anaemia?

Answer 35

impaired growth

risk of end organ damge with recurrent crisis i.e. pulmonary hypertension/stroke

Question 36

what are the management options for sickle cell anaemia?

Answer 36

folic acid supplementation

hydroxycarbamide

regular transfusion in select cases

Question 37

why is hydroxycarbamide helpful in managing sickle cell anaemia?

Answer 37

tricks body into producing HbF instead of HbS

Question 38

how is liquid chromatography helpful in haematology?

Answer 38

height of peak corresponds to how much of that Hb is present