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At Least I Know He’s From a Good Family
Remember
me? It’s my
turn today.
At Least I Know He’s From a Good Family
Susan makes an appointment with the genetics staff.
Anyways, we’re really
This guy, he’s
serious
I’m developing
about each
a
Vietnamese. His
other,
relationship
and I want
with to
mother is Vietnamese
make
a special
sureguy
thatbut
our
anyway. And I’ve heard
kids
I’m concerned
would be
about thalassemia.
ok…you
about birth
know with all
Isn’t that the one that
the
defects.
problems we
Southeast Asians can
have.
get?
It’s more
Ok,
so let’s
common
toreview
that
thalassemia.
area of the
world.
B-Thalassemia
• Gene disorder: Autosomal
recessive
• Red blood cell deficiency
• Common ethnicities:
– African decent
– Mediterranean decent
– SE Asian decent
• Early heart & spleen
disease
• Treatments: Blood
transfusions
At Least I Know He’s From a Good Family
His father and
my father are
No.
Oh
Myboy…that’s
ancestors
the
brothers.
Dan is are
from
England.
thing They
I wanted
myother
first
cousin.
came
to talk
overtoon
you
theabout…
Mayflower I think.
Well, as long as
you’re not related to
this guy, I don’t
think thalassemia
should
beparents
a
Are your
problem.
Southeast Asian,
Italian, or from the
Mediterranean?
The geneticist explains that while Dan has about a 6% chance of
carrying the gene for thalassemia, the fact
that Susan
first of
Everyone
carriesisahis
handful
cousin doesn’t increase their chance of having
a child
recessive
geneswith
that could be
thalassemia as much as it would if Susan’s
familythey
waspair
of up in the
harmful
The vastifmajority
of children
offspring.
If Susan
you’re
Mediterranean decent because the likelihood
carries
the
born tothat
first
cousinsunrelated,
are
the
odds
for these
thalassemia gene is about 1 in 100, no higher
than
it is
anyone
healthy.
There
is for
a genes
higher
rate
pairing
up areloss
small.
who is not Mediterranean or Southeast Asian.
of pregnancy
and
I’ve heard that children born to first
cousins are almost always mentally
retarded, still born, or have some serious
defect. This makes me hesitant to allow
the relationship to grow.
congenital malformation. But
the odds are in your favor.
But since you and Dan are
closely related, the likelihood
that you and Dan are both
carries is greater.
Susan and Dan are offered carrier testing just to be safe. The geneticist
calculates that even if Dan does carry a gene for thalassemia, the likelihood
that they could have a child with this condition is about 1 in 400.
Odds
Susan
Is a
Carrier
Assuming
Dan is a
carrier
Odds 2
carriers
produce an
affected
child
1/100
1
1/4
Susan
carrier
Dan
carrier
Odds 2
carriers
produce
an
affected
child
1/2
1/8
1/4
At Least I Know He’s From a Good Family
No thank you. My niece is doing ok. Even if we
carry the gene, I don’t think that it would change
anything. If we ever have children, the doctors are
going to be especially careful with PKU testing. I
won’t worry about it now.
Would you both
like to be tested
for PKU?
Essay
• Recently, a man and a woman planning to
be married found out that they were
biologically brother and sister. Both had
been given up for adoption and had been
raised by different families, never knowing
of the other's existence. Do you think they
should be allowed to be married?