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Medicine

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Hematology

Question
10 out of 19
 

Cause of alpha thalassemia (AIIMS May 2011)



A Deletion of alpha genes
B Deletion of beta genes

C Excess of alpha gene
D Single amino acid substitution in alpha chain

Ans. A

Deletion of alpha genes

HbH is characterized by deletion of Three alpha chain genes.

The four classic alpha-thalassemias, most common in Asians, are: (Ref. Robbins,7th ed., Pg. 634)

Type of alpha thalassemias:

Characterized by:

1

Silent career

One of the four alpha-globin loci is deleted;

2

Alpha-thalassemia- trait

Two loci deleted;

3

HbH disease

Three loci deleted;

4

Hydrops fetalis with Hb Bart's

All four loci deleted.

The α Thalassemias (Ref. Hari-. 18th ed., Pg. 859, table 104.4)

Condition

Hemoglobin A, %

Hemoglobin H (β4), %

Hemoglobin Level, g/L (g/dL)

MCV, fL

Normal

97

0

150 (15)

90

Silent thalassemia: –α/αα

98–100

0

150 (15)

90

Thalassemia trait: –α/–α

or – /αα

85–95

Rare red blood cell inclusions

120–130 (12–13)

70–80

HbH disease: – –/–α

70–95

5–30

60–100 (6–10)

60–70

Hydrops fetalis: – –/– –

0

5–10b

Fatal in utero or at birth

(Ref. Hari- 18th ed., Pg. 859)

Hematology Flashcard List

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