Hemoglobin Variation
Hemoglobin Variation
Dr Sunita Mittal
Learning Objectives
▪
Different Hemoglobin
variants
▪
Characteristics of Hemoglobin
variants and Hb
▪
Different Hemoglobin
combinations
Hemoglobin V
ariants
•
There must be 2 Alpha and 2 non alpha for oxygen carrying
function, which differs at different stages of foetal and early
neonatal life
•
Normal adult hemoglobin (HbA) consists of four polypeptide
chains
α
2
β
2
•
Normally in adult blood, small quantities of two other varieties of
hemoglobins i.e. HbA
2
and HbF are found.
Hemoglobin V
ariants
Normal Hemoglobin V
ariants
HbA
(
α
2
β
2
)
96
%
to 98
%
This is basic form of Hb which is important in transport of gases O
2
and CO
2
.
HbA
2
(
α
2
δ
2
)
After 6 months to 1 year = 02% to 03
%
Normal Hemoglobin V
ariants
Fetal hemoglobin (
α
2
γ
2
)
α
-
141 amino acids
Lifespan of RBC containing HBF is decreased to
80 days
only
Embryonic Hb
Hb
ε
Gower-1
(
ζ
2
ε
2
)
Primary Hb in embryonic life ≈ 8 wks
Portland-1 (
ζ
2
γ
2
) is the ζ-substituted counterpart of fetal HbF (α
2
γ
2
)
(By 12 weeks of
gestation, embryonic Hb changes into HbF.
Hb Portland-2 (ζ
2
β
2
) since it occurs only in cases of an extreme type of α-thalassemia.
Normal Hemoglobin V
ariants
Importance of Fetal hemoglobin (
α
2
γ
2
) in fetal life
▪
HbF can take up large volume of oxygen at
lower PO
2.
Abnormal hemoglobin Variants - Hemoglobinopathies
GLOBIN CHAINS
The genes for the synthesis of globin are present on chromosome 16 (
α
) and
chromosome 11 (
β
).
This determines the different variants of hemoglobin (Normal and abnormal) present at
different ages.
G
lobin
genes and hemoglobin molecules
▪
First molecular disease to be recognized.
▪
α
chains are normal and basic abnormality is in beta chain due to a point
mutation.
Sickle Cell Disease (HbS)
▪
SICKLE CELL DISEASE
Homozygous -HBSS
▪
SICKLE CELL TRAIT
Heterozygous - HbAS
Sickle Cell Disease
• Most common Hb variant
Hb S molecules are only 20% as soluble as Hb
A in deoxygenated blood,
↓
low oxygen tension, Hb S molecules
polymerize
↓
causing sickle shaped RBCs
↓
Sickle Cell Disease
Jaundice
is also
called as
------------------------------when serum
bilirubin is above --------------------
-
The baby at birth has ------------------------------------------------------------ and excessive RBCs destruction
80% of ------------------------------- is excreted in feces as ---------------------------, which gives brown color of stool and
20% through enterohepatic circulation is excreted in urine as ----------------, which gives yellow color of urine
Pre-hepatic Jaundice
is caused by an increased rate of ---------------------------------------------------------------------
Physiological Jaundice in newborns occurs due to
------------------------------------------------------------------------------
H
epatic cause of
physiological jaundice in newborns
------------------------------------------------------------------------------------
Kernicterus may occur in new born because ------------------------------and when ------------------------------------------
Self Assessment
Thank you
Uncover the characteristics and variations of hemoglobin, including embryonic, fetal, and adult forms. Learn about the importance of fetal hemoglobin in fetal life and abnormal hemoglobin variants known as hemoglobinopathies. Dive into the structural differences, functions, and genetic determinants that contribute to the diverse hemoglobin profiles throughout different life stages.
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Presentation Transcript
Hemoglobin Variation Dr Sunita Mittal
Learning Objectives Different Hemoglobin variants Characteristics of Hemoglobin variants and Hb Different Hemoglobin combinations
Hemoglobin Variants There must be 2 Alpha and 2 non alpha for oxygen carrying function, which differs at different stages of foetal and early neonatal life Normal adult hemoglobin (HbA) consists of four polypeptide chains 2 2 Normally in adult blood, small quantities of two other varieties of hemoglobins i.e. HbA2 and HbF are found.
Normal Hemoglobin Variants Type Embryonic Hb Fetal Hb Adult Hb Hb Gower-1 Hb F Hb A Hb A2 2 2 structure 2 2 2 2 2 2 Primary Hb in embryonic life 8 wks Normal % 0.5-0.8 % 96-98 % 2.0-3.0 %
Normal Hemoglobin Variants HbA( 2 2) 96% to 98% This is basic form of Hb which is important in transport of gases O2 and CO2. HbA2 ( 2 2) After 6 months to 1 year = 02% to 03%
Normal Hemoglobin Variants Fetal hemoglobin ( 2 2) - 141 amino acids Lifespan of RBC containing HBF is decreased to 80 days only Embryonic Hb Hb Gower-1 ( 2 2) Primary Hb in embryonic life 8 wks Portland-1 ( 2 2) is the -substituted counterpart of fetal HbF ( 2 2) (By 12 weeks of gestation, embryonic Hb changes into HbF. Hb Portland-2 ( 2 2) since it occurs only in cases of an extreme type of -thalassemia.
Importance of Fetal hemoglobin (22) in fetal life HbF can take up large volume of oxygen at lower PO2.
Abnormal hemoglobin Variants - Hemoglobinopathies GLOBIN CHAINS The genes for the synthesis of globin are present on chromosome 16 ( ) and chromosome 11 ( ). This determines the different variants of hemoglobin (Normal and abnormal) present at different ages.
Sickle Cell Disease (HbS) First molecular disease to be recognized. chains are normal and basic abnormality is in beta chain due to a point mutation. SICKLE CELL DISEASE Homozygous -HBSS SICKLE CELL TRAIT Heterozygous - HbAS
Sickle Cell Disease Most common Hb variant
Sickle Cell Disease Hb S molecules are only 20% as soluble as Hb A in deoxygenated blood, low oxygen tension, Hb S molecules polymerize causing sickle shaped RBCs
Self Assessment Jaundice is also called as ------------------------------when serum bilirubin is above --------------------- The baby at birth has ------------------------------------------------------------ and excessive RBCs destruction 80% of ------------------------------- is excreted in feces as ---------------------------, which gives brown color of stool and 20% through enterohepatic circulation is excreted in urine as ----------------, which gives yellow color of urine Pre-hepatic Jaundice is caused by an increased rate of --------------------------------------------------------------------- Physiological Jaundice in newborns occurs due to ------------------------------------------------------------------------------ Hepatic cause of physiological jaundice in newborns ------------------------------------------------------------------------------------ Kernicterus may occur in new born because ------------------------------and when ------------------------------------------
