Haemoglobin is the pigment that transports oxygen in the blood.
It is in the red blood cells and this is what gives blood its
red colour. There are many different types of haemoglobin. Haemoglobin
S, or sickle haemoglobin, is responsible for Sickle Cell Anaemia.
Sickle Cell
Anaemia is hereditary, meaning that it is the passing on of
characteristics from the parents to the child. This means that
you can not 'catch it' from someone, like a cold or an
STD (sexually transmitted disease).
Sickle Cell
Anaemia can be passed onto the child, through haemoglobin heritage,
in the following ways:
Click images to see a bigger image and information.
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This diagram shows the Haemoglobin (or HB) type for both
parents as AA. This is the
'normal' haemoglobin type.
This shows that however the genetics go, the child will
always have both normal haemoglobin genes.
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However, this diagram shows that out of both haemoglobin
types, one of the parents has both 'normal'
haemoglobin genes, and the other parent has one 'normal'
haemoglobin gene (A)
and one haemoglobin
S gene (S).
This means that the child will now have a 50% chance
of carrying both 'normal'
haemoglobin genes, and a 50% chance of carrying one
'normal' haemoglobin gene and
one haemoglobin S
gene.
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*added 10.feb.03 |
This diagram shows that one parent has both 'normal'
(A) haemoglobin genes, and
the other parent has both Sickle
genes.
This means that whichever way the genetics goes the child
will only have Sickle Cell Trait. This is the carrier
gene for Sickle Cell (i.e. to pass itself on genetically).
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This diagram shows that both parents have one 'normal'
haemoglobin gene (A) and one
haemoglobin S gene (S)
(as was in my case).
This means that the child has 1 in 4 (25%)
chance of having 'normal' haemoglobin,
a 2 in 4 (50%) chance of having one 'normal'
and one haemoglobin S gene,
therefore having Sickle Cell Trait, and a 1 in 4
chance of having Sickle Cell Anaemia.
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This diagram shows that one parent carries one 'normal'
haemoglobin gene and one Sickle gene,
and the other carries both Sickle
genes.
This means that the child will have a 2
in 4 (50%) chance of having one 'normal' haemoglobin
gene and one haemoglobin S gene,
and a 2 in 4 (50%) chance of having both
haemoglobin S genes.
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Unfortunately, in this diagram two haemoglobin
S genes are carried by both parents. The child will
have a 100% chance of inheriting Sickle
Cell Anaemia.
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