Transcript X h X h X h Y X h X h X H Y X H X h

Scene II: Will Alan ever play for the
Lakers?
After this lesson, the students will be able to:
1) Explain x-linked inheritance using Factor VIII
deficiency (hemophilia) as an example;
2) Describe the treatment for hemophilia;
3) Explain the importance of early diagnosis and
carrier testing of hemophilia; and
4) Describe some societal issues associated with
hemophilia and its treatment.
Alan’s Situation
Alan suffers a painful knee injury while shooting baskets in his
parents’ driveway. Examination at the emergency room
indicates that Alan has a bad sprain, in addition to bleeding
within the knee joint. Further testing reveals a deficiency of
Factor VIII, and a diagnosis of hemophilia is made. Stacy is
found to have reduced Factor VIII levels, consistent with her
being a hemophilia carrier.
Alan’s Situation (contd.)
XH Xh
XH Y
since
you’re
a
It’sStacy,
a good
thing
you have
a
carrier
must
But
since
Alan
is ahave
boy heor
“back
up”you
X
chromosome
Stacy, Alanreceived
mustXhave
inherited
your X
one
chromosome
that
your
Yhistory
Paul, since
you
have
noFactor
of
you
would
also
have VIII
The
gene
for
chromosome
that does
not make
factor
factor
VIII and
chromosome.
hemophilia
and
youXhave
normal
factor
hemophilia.
isproduces
on the
chromosome.
VIII. He hasonce
“no back”
X
chromosome.
does
not. is fine.
VIII, your Hemophilia
only Xthat
chromosome
is a sexHis disorder has gone unnoticed all these
linked disorder.
years until his basketball injury.
What is Hemophilia?
• AKA: Factor VIII
deficiency
• Blood clotting disorder
usually affecting males
– 1 in 5,000
• Abnormal protein “Factor
VIII” created
– Factor VIII necessary
for blood clotting
– Clotting takes longer
• Severity varies based on
amount of Factor VIII
produced
• Sex-linked disorder (found
on X chromosome)
Healthy girl
Healthy girl
(carrier)
Healthy boy
hemophiliac
boy
Key:
H = healthy
h = hemophilia
30 seconds: Discuss with your neighbor.
Jen is a healthy carrier (XH Xh) of hemophilia and
Adam has no history in his family (XH Y).
What is the probability of:
Healthy girl
Healthy girl
(carrier)
2010
Healthy boy
Hemophiliac
boy
2013
¾
x
¾
a. Daughter with
hemophilia?
0%
b. Carrier child?
25%
c. Child with hemophilia?
25%
d. Two healthy children?
9/16 (56%)
1 minute: Discuss with your neighbor
Kelly is a healthy carrier of hemophilia, but Jim
suffers from the disease.
What is the probability of
getting a:
Healthy girl
(carrier)
Hemophilia
girl
Healthy boy
Hemophilia
boy
Healthy son?
25%
Healthy daughter?
25%
Child with hemophilia?
50%
Carrier child?
25%
Hemophilia is a sex linked disorder. Lana does not have
hemophilia even though her mother did. Sterling (Lana’s
husband) is a hemophiliac. Their first child Barry is healthy but
their other child Malorie is a hemophiliac. Draw a Pedigree for
this family and a Punnett square for Lana and Sterling.
What is the
probability of
getting a:
Xh Xh
Lana’s
mother
Lana
XH Xh
Barry
Healthy girl
(carrier)
Healthy boy
Hemophiliac
girl
Hemophiliac
boy
XH Y
Sterling
Xh Y
Malorie
Xh Xh
a. Healthy son?
25%
b. Healthy
daughter?
25%
c. Child with
hemophilia?
50%
d. Carrier child?
25%
Treatments
• Factor VIII Replacement:
– Intravenous injections of
Factor VIII
– Causes clotting
• Joint Replacement
– Knee, hip, ankle
replacement if arthritis is
severe
• Regular exercise for strong
muscles to protect the weak
joints
Alan’s Situation
Alan is starting on Factor
VIII home infusion. His
parents are taught how to
inject Alan with Factor
VIII that has been
removed from donated
blood, purified, and
packaged for use.
The Factor VIII can be kept
at home and prepared for
injection when Alan feels
that bleeding has
occurred. The Factor VIII
can also be taken with
them on trips.
Factor VIII Infusions
• Objective: replace missing clotting factor
• When used:
– Used at time of bleeding to prevent tissue
damage
– Prior to and during surgery
• Cost: over $100,000/year (beyond lifetime cost
of many insurance plans)
• Prior to 1984: HIV prevalent in the Hemophilia
community (70-90%)
Alan’s Situation
What about
AIDS? If Factor
VIII comes from
donated blood,
can he catch
AIDS?
AIDS was a threat to
hemophiliacs years ago, but
more strict donor guidelines and
heat-treating of blood reduces
the chances of AIDS being a
problem.
Alan’s Situation
I remember
that boy in
Frank’s
school who
Hehad
What
gotHIV
HIV
must it
from
have
aa
blood
been
about
year
transfusion
like
ago.for the
during
boyheart
and his
surgery.
family?
Several parents
demanded that the
boy be removed
from school,
threatening to
remove their own
children if their
demands were not
met.
Stacy remembered
following the issue
in the newspapers,
but she took no
particular position
on the issue.
Expanding the Chance Family
Absolutely NOT!
And if you tell her
anything about
Yes,
one.
And a
Alan’s
hemophilia,
brother,
David.
I’ll sue you
and this
place for everything
you’re worth.”
Stacy, since hemophilia is X-linked
and you’re a
carrier,
it’smight
important
Your
sister
also be a
that we contact
other
carrier.
Youfamily
should bring her
to date
on this and
members ofup
yours
to discuss
theirask
to make
appointment
risk of beingher
carriers.
Doan
you
have
with us.
any sisters?
Chances’ Choices Essay #2:
Does Martha’s right to know about her risk of
being a hemophilia carrier take precedence
over Stacy’s right to keep her family’s medical
records confidential?
•
Essay Format:
– Ink or typed (no pencil)
– Add title and date
– Minimal length = ¾ page
– If typed: 1” margins, 12-point times new roman font, double spaced.
– Complete essays (Introduction, body, conclusion)
– Spellcheck and proofread
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
1
2
XH Y
3
4
5
XH Y
8
9
XH Y
6
7
Xh Y
10
11
XH Y
XH Y
14
Xh Y
Hint: Only 1 person is unknown.
XH Y
12
13
Males:
XH Y
or
Xh Y
Xh Y
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
3
XH Y
1Y
2Xh
XH Y
XH Xh
4
5
Xh Y
XH
from mother
8
9
XH Y
XH
6
10
11
XH Y
XH Y
14
Xh Y
Hint: Only 1 person is unknown.
12
XH
7
XH Y
XH
from father
Females:
XHXH
or
XHXh
or
XhXh
13
Xh Y
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
3
XH Y
8
9
XH Y
XH
1
2
XH Y
XH Xh
4
5
Xh Y
XH
10
11
XH Y
XH Y
14
Xh Y
Hint: Only 1 person is unknown.
12
XH
X6h
7
Y
XH Xh
XH Y
13
Females:
Xh Y
H
H
X X
or
from father
XHXh from mother
or
XhXh
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
3
XH Y
Y
8
XH Y
11
XH Xh
XH Y
XH Y
from father
from mother
XH Y
XH Xh
5
Xh Y
XH
10
Xh Y
2
4
X9h
14
1
12
XH
6
7
XH Xh
XH Y
Females:
XHXH
or
XHXh
or
XhXh
13
Xh Y
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
X3H
XH Y
8
XH Y
2
XH Y
XH Xh
X4h
5
Xh Y
XH Xh
9
10
11
XH Xh
XH Y
XH Y
14
1
from
fromfather
mother
Xh Y
Hint: Only 1 person is unknown.
12
XH
6
7
XH Xh
XH Y
Females:
XHXH
or
XHXh
or
XhXh
13
Xh Y
Key
XH = healthy
Xh = hemophilia
Sex linked recessive: Hemophilia
X3H
XH Y
8
9
10
1
2
XH Y
XH Xh
4
XH
11
5
Xh Y
Xh
12
6
7
XH Xh
XH Y
Females:
XH Y
XH Xh
XH X?
XHXH
or
from
mother
from father
14
XHXh
Xh Y
or
XhXh
Hint: Only 1 person is unknown.
XH Y
XH Y
13
Xh Y