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Hemophilia – a Case Study
What are symptoms?
• excessive or spontaneous bleeding into
–
–
–
–
joints,
muscles,
brain,
or other internal organs
• oozing following an injury or surgery,
(having a tooth pulled)
• clotting is slowed or nonexistent
Molecular Genetics of
Hemophilia
• Changes in the “F8” gene
– instructions for coagulation factor VIII
(protein).
http://ghr.nlm.nih.gov/gene/F8#conditions
Biochemistry of the disorder
wikipedia
Mode of inheritance
• X-linked recessive
Type of Mutation
• most common mutation in people with
severe hemophilia A is
– a rearrangement of genetic material
called an inversion.
– involves a large segment of the F8 gene.
Inversion Mutation
History of the disease
• Dr. John Otto (1803),
– a Philadelphian physician,
– wrote of "a hemorrhagic disposition existing in
certain families"
– called the affected males "bleeders."
• recognized the disorder was
– hereditary
– affected mostly males
– passed down by healthy females.
Incidence
• About 18,000 people in the United States
• Two types:
– Hemophilia A
• (classic type)
• represents 80% of haemophilia cases
– Hemophilia B
• in 4,000 to 1 in 5,000 males worldwide
Treatment & Maintenance
• no cure for haemophilia
• controlled with regular infusions of the
deficient clotting factor
• genetically engineered factor VIII from
the genes of Chinese hamster ovary cells
– higher purity and safety,
– extremely expensive, and
– not generally available
What should parents do?
• Determine severity of the disease
• Get tested
• Monitor pregnancies
• Seek genetic counseling
Future possibilities
• More widely available genetically
engineered protein
• Gene therapy