SCDx is a blood
disorder in which the Red Blood Cells (RBC) loose their discoid shape and
become sickle-shaped thus losing their ability to transport oxygen and also
blocking arteries thereby preventing blood flow to the organs. Sufferers of the
disease are commonly referred to as "sicklers" or "SS". They possess the genotype
SS. Normal individuals are AA while AS is the carrier state. They suffer
agonizing pains known as "crisis" leading to frequent and recurrent
visits to the hospital.
My patient is a 29
year old woman and she already has her 4th child. Lucky woman you are, I
teased. At 29, four kids already.
Not that lucky she
replied. My first child, a boy is AA, the second, a girl is AS while the third
is SS. This 3 month old I'm carrying, only time will tell what his genotype is.
The third child
had been falling ill frequently and it was discovered that she suffered from
SCDx. It was at that time that the couple also realized they were both carriers,
AS-AS. They had no pre-marriage testing.
I had many
questions on my mind for her like, "would you have married him if you
knew from the outset that you were both carriers?"how did you feel knowing you have given birth to a sickler?" but I asked her only
one - Why did you go ahead to having a fourth child after discovering that your
third child is a sickler? I would have
expected that you'd stop child bearing after three kids. Is it an automated
natural compulsion to procreate or have you calculated the probability and
found out that the fourth cannot be sickler?
As the full effects of the symptoms manifest as the child grows older, I wonder how it will impact on the whole family and how they would handle it.
The truth is this,
the occurrence of SCDx actually lies only in the hands of God. There are
families who had no sicklers, while there are others who had multiple. However,
the choice "to" or "not to" take the risk lies in our own
hands.
This peculiar case
got me calculating probabilities. I disliked the topic back in secondary
school. Circle geometry was my favorite. Just curious, for you math gurus, what
is the probability that (a) the fourth child would be a sickler and (b) what is
the probability that he would not?