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Pathology > Moleculer Basis Of Hemoglobinopathies > Flashcards

Moleculer Basis Of Hemoglobinopathies Flashcards

1
Q

What are Hemoglobinopathies

A

are a diverse group of inherited blood disorders that result from variations in the structure and/or synthesis of hemoglobin.

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2
Q

Hemoglobinopathies mainly include

A

1- thalassemias

2- sickle cell diseases (SCD)

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3
Q

If a Hemoglobinopathies disease is h eterogeneous

A

then multiple genes and alleles are causing it not only one ( Diverse]

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4
Q

What is the diffrence btw adult hemoglobin (HbA) and Fetal hemoglobin (HbF)

A

Normal adult hemoglobin (HbA) is a tetramer of two α chains and two β chains (α2β2). Fetal hemoglobin (HbF) is a is a tetramer of two α chains and two γ chains (α2γ2).

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5
Q

HbA2

What is it

A

is the third normal adult hemoglobin and it consists of 2 alpha and 2 delta subunits. This type constitutes only 2.5% of the
blood.

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6
Q

We have the fetal blood in our blood its about

A

2.5%

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7
Q

HBA in adult is about ….%

A

97

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8
Q

The globin genes are located in ….chromosomes

A

2

ch16 and 11

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9
Q

Why the alpha globin gene dosenot follow Mendalian inheritance

A

Bcs it has double the standered smount of genes —-> 4 genes

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10
Q

What is the importance of The locus control region (LCR

A

is the one reponsible for the switch between the transcription of the gamma globin chain gene and the b-globin chain gene.
- switch from embryonic to fetal to adult

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11
Q

LCR only found in … and …..

A

gamma globin chain gene and the b-globin chain gene

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12
Q

What is the importance of PYR complex

A

controls the switch of expression from

  • gamma. To
  • beta
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13
Q

Why alpha globin genes synthesis considered Constant

A

We have 2 copies of alpha and therefore 4 genes in our body. It is continuously expressed (Constant)

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14
Q

What happened to gamma globin gene synthesis

A

gamma globin dramatically decreases at birth

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15
Q

Notice how after birth, the synthesis of ….globin decreases and the …. globin production isincreased

A
  • gamma

- beta

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16
Q

gamma globinisreplacedalmost completely by beta at the age of ….. weeks

A

50

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17
Q

Adult can have a traces of gamma

A

T

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18
Q

Thalassemia is

A

Reduction in either alpha or beta globin chain level is low but the structure is normal

19
Q

Thalassemia can be classified as

A
  1. α-thalassemia: patients have a defective expression of α-globin genes
  2. β-thalassemia: patients have a defective expression of β-globin gene
20
Q

…….patesints requiring lifelong blood transfusions with complications in multiple organ systems.

A

Thalassemia

21
Q

(αα/αα) The deletion or inactivation of only one α-globin gene usually results in …..

A

insignificant hematologic findings

22
Q

What is the result in insignificant hematologic findings

A

silent carriers)

  • normal phenotype
  • genotypes (α-/αα) or (αα/α-)
23
Q

When 2 α-globin genes are deleted or inactivated, either on the same chromosome (αα/–) [southeast Asia] (cis) or on opposite
chromosomes (α-/α-) [African] (trans.), the affected person has

A

borderline anemia

24
Q

What is borderline anemia

A

On the line between anemic or not

25
Q

borderline anemia, characterized by….rbcs

A

microcytic

hypochromic

26
Q

HbH disease caused by

A

The deletion of three a-globin [only one functional α-globin gene]

27
Q

HbH disease: patients usually have anemia at ….. but ……

A

At birth

Not lethal

28
Q

intrauterine anemia happened bcz of

A

Hb Bart’s hydrops fetalis syndrome

29
Q

There is a difference between HbH disease and HbH hemoglobin as well as Hb Bart’s hemoglobin and Hb Bart’s hydrops fetalis syndrome.

A

T

30
Q

Level of. Hb Bart’s, above 15% at birth is an indicative of HbH disease

A

T

31
Q

Hb Bart’s (All gamma chains hemoglobin) can be present in HbH disease, but in small amounts that is not fatal like in Hb Bart’s Hydrops Fetalis syndrome

A

T

32
Q

If you have 100% Hb barts then it will cause prenatal/postnatal death.

A

T

33
Q

excess β-globin chains form β4 homotetramers [HbH Hb] leads to

A

severe form of α-thalassemia.

34
Q

What is the diffrence btw HbH disease and HbH hemoglobin

A
  • HbH Hb : homotetramer structure of 4 beta subunits

* HbH disease : Mutation in 3 genes when only one alpha is functional the other 3 are not working

35
Q

HbH disease are not transfusion-dependent but may require transfusion support for

A

infections and other oxidative stresses.

36
Q

The most common nondeletional form of HbH disease is

A

HbH Constant Spring

37
Q

what is β-thalassemia

A

The aggregation/deposit of alpha globins lead to ineffective erythropoesis leading to premature death of RBCs.

38
Q

Heinz bodies found in ….

A

hBH Erythrocyte

39
Q

β-Thalassemia

A

β-thalassemia is caused by the reduction (β+) or absence (β0) of β globin chains synthesis.

40
Q

There are three main types of β-thalassemia

A
  1. β-thalassemia carrier state or minor (clinically asymptomatic; heterozygous)
  2. β-thalassemia intermedia, (clinically and genotypically very heterogeneous)
  3. β-thalassemia major (severe transfusion-dependent anaemia)
41
Q

The accurate identification of thalassemia intermedia versus thalassemia minor and major can be difficult if based on

A

clinical presentation alone

42
Q

is the most accurate approach for distinguishing between the different types of β-Thalassemia.

A

Genetic analysis

43
Q

Half of clinically severe thalassemia actually have the ….genotype

A

HbE/β- thalassemia genotype.

44
Q

There were two siblings with HbE/β-thalassemia and one of them died immediately after birth while the other survived. If u looked at the genetic composition what will u find ?

A

The one who died had a mutated α chain because we said it becomes more severe when its combined with alpha mutation!

Pathology (6 decks)

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