Thalassemia : Definition, Pathogenesis, Treatment and MCQs for NEET, GPAT, CSIR NET, UPSC Exam
” The thalassemia is a heterogeneous group of mendalian disorder, all characterized by lack of or decreased synthesis of either the alpha or the beta globin chain of hemoglobin A (α2β2).”
1.] Thalassemia, unlike haemoglobinopathies which are the qualitative disorders of hemoglobin, are quantitative abnormalities of polypeptide globin chain synthesis.
α – THALASSEMIA :-
In α – thalassemia major, the obvious cause of anemia is the inability to synthesis the adult hemoglobin, while in alpha thalassemia trait there is reduced production of normal adult hemoglobin.
PATHOGENESIS OF α – THALASSEMIA :-
1.] α – thalassemia is a disorder in which there is defective synthesis of α – globin chain resulting in decreased production of hemoglobin that contain α – chain i.e; HbA, HbA2 and HbF.
2.] Most commonly α – thalassemia is due to the deletion of one or more of the α – chain genes located on short arm of chromosome – 16.
3.] α – thalassemia is classified into 4 – types :
- Four α – gene deletion : Hb Brat’s hydrops foetalis.
- Three α – gene deletion : HbH disease.
- Two α – gene deletion : α – thalassemia trait.
- One α – gene deletion : α – thalassemia trait (carrier).
β – THALASSEMIA :-
The abnormality common to all β – thalassemia is a total lack or a reduction in the synthesis of structurally normal β – globin chain with unimpaired synthesis of alpha chains.
PATHOGENESIS OF β – THALASSEMIA :-
1.] Most of the β – thalassemia arises from different types of mutation of β – globin chain resulting from single base changes, like the βº is used to indicate the complete absence of β – globin chain synthesis etc.
2.] Some of the important mutation having effects on β – globin chain synthesis are under :\
- Transcription defect
- Translation defect
- mRNA splicing defect
3.] Depending upon the extend of reduction of β – thalassemia chain synthesis, there are three types of β – thalassemia :
A.) Homozygous form : β – thalassemia major, it is the most severe form of congenital haemolytic anemia. It is further of two types :
- βº thalassemia : complete absence of β – chain synthesis.
- β+ thalassemia : complete suppression of β – chain synthesis.
B.) β – thalassemia intermedia : It is β – thalassemia of intermediate degree of severity that does not require regular blood transfusion.
C.) Heterozygous form : β – thalassemia minor (trait), it is a mild asymptomatic condition in which there is moderate suppression of β – chain synthesis.
TREATMENT :-
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MULTIPLE CHOICE QUESTIONS: –
1.] This is not a symptom of thalassemia?
a. Abdominal pain
b. Weakness and slow growth
c. Dark urine
d. Facial bone deformation
2.] Which of the following is the cause of α-thalassemia?
a. Deletion of alpha gene
b. Deletion of beta gene
c. Excess of alpha gene
d. Single amino acid substitution in alpha chain
3.] True about beta thalassemia trait is?
a. Increased HbF
b. Increased HbA2
c. Microcytosis
d. Severe anemia
e. Target cell
4.] In α-thalassemia, which of the following is a finding?
a. No beta-chain
b. Excess alpha-chain
c. No alpha-chain
d. Relative of excess of beta, gamma, and delta chain
5.] All are seen in thalassemia major except?
a. Transfusion dependency
b. Splenoheptatomegaly
c. Ineffective erythropoiesis
d. Macrocytic anaemia
6.] This type of thalassemia disease is cooley anaemia?
a. Alloimmunization
b. β-thalassemia
c. α-thalassemia
d. None of the above
7.] Treatment given to thalassemia patients?
a. Stem cell or bone marrow transplant
b. Blood transfusion
c. Iron chelation
d. All of the above
8.] Possible complication of thalassemia?
a. Infection
b. Iron overload
c. Only b
d. Both (a) and (b)
9.] The complication that occur in severe thalassemia?
a. Enlarged spleen
b. Bone deformities
c. Problem with heart
d. All of the above
10.] Factors leading to an increase in the risk of thalassemia?
a. Certain ancestry
b. Family history of thalassemia
c. Only b
d. Both (a) and (b)
SOLUTIONS: –
1.] (a) Abdominal pain
2.] (a) Deletion of alpha-gene
3.] (a), (b), (c) and (e)
4.] (d) Relative of excess beta, gamma and delta chain
5.] (d) Macrocytic anaemia
6.] (b) β-thalassemia
7.] (d)
8.] (d)
9.] (d)
10.] (d)
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REFERENCES :-
1.] Textbook of Pathology By Harsh Mohan; 7th edition; Page no.296 – 301.
2.] Robbin’s Basic Pathology; 5th edition; Page no. 596 – 601.