Scene II: Will Alan ever play for the Lakers?. After this lesson, the students will be able to: Explain x-linked inheritance using Factor VIII deficiency (hemophilia) as an example; Describe the treatment for hemophilia;
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After this lesson, the students will be able to:
Explain x-linked inheritance using Factor VIII deficiency (hemophilia) as an example;
Describe the treatment for hemophilia;
Explain the importance of early diagnosis and carrier testing of hemophilia; and
Describe some societal issues associated with hemophilia and its treatment.
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.
Stacy, since you’re a carrier you must have one X chromosome that produces factor VIII and once that does not.
It’s a good thing you have a “back up” X chromosome or you would also have hemophilia.
But since Alan is a boy he received your Y chromosome.
Stacy, Alan must have inherited your X chromosome that does not make factor VIII. He has “no back” X chromosome. His disorder has gone unnoticed all these years until his basketball injury.
The gene for Factor VIII is on the X chromosome. Hemophilia is a sex-linked disorder.
Paul, since you have no history of hemophilia and you have normal factor VIII, your only X chromosome is fine.
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)What is Hemophilia?
H = healthy
h = hemophilia
Healthy girl (carrier)
Child with hemophilia?
25%Just for practice: Kelly is a healthy carrier of hemophilia, but Jim suffers from the disease.
Healthy girl (carrier)
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.
After the increased risk of hepatitis is discussed, immunizations against Hepatitis B and D are scheduled.
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.
What about AIDS? If Factor VIII comes from donated blood, can he catch AIDS?
Let’s see if our insurance will pay for Factor VIII.
Well that’s reassuring.
I remember that boy in Frank’s school who had HIV about a year ago.
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.
He got HIV from a blood transfusion during heart surgery.
What must it have been like for the boy and his family?
Stacy, since hemophilia is X-linked and you’re a carrier, it’s important that we contact other family members of yours to discuss their risk of being carriers. Do you have any sisters?
Absolutely NOT! And if you tell her anything about Alan’s hemophilia, I’ll sue you and this place for everything you’re worth.”
Your sister might also be a carrier. You should bring her up to date on this and ask her to make an appointment with us.
Yes, one. And a brother, David.
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?