CH 122 HEMOPHILIA A AND HEMOPHILIA B Flashcards
Hemophilia A results when mutations occur in the F8 gene located on the
long arm of the X-chromosome (X-q28)
T/F
All daughters of a hemophilic male are carriers of hemophilia, whereas all sons are normal.
True
Daughters of carriers have a ___% chance of being a carrier, whereas sons of carriers have a ___% chance of having hemophilia.
50
50
One of the most common mutations, accounting for 40% to 50% of severe hemophilia A patients
“combined gene inversion and crossing over” that disrupts the F8 gene
Although extremely rare, Hemophilia A may occur in females with
X chromosomal abnormalities such as Turner syndrome,
X chromosomal mosaicism, and
other X chromosomal defects
T/F
If the normal X chromosome is inactivated disproportionately (“imbalanced X inactivation”) in a carrier female, factor VIII levels may be sufficiently low to cause bleeding manifestations.
True
At least ___% of the cases of hemophilia are a result of sponta- neous (de novo) mutations.
Most of these occur at _____ in the F8 gene.
30
CpG dinucleotides
The current standard for identifying carrier status is through
direct gene sequencing
Prenatal diagnosis of hemophilia now can be performed almost routinely.
If the fetus is a male, sufficient cells can be obtained to perform DNA analysis using the methods…
chromosomal analysis of cells by amniocentesis (at 16 weeks of gestation)
by chorionic villus sampling at week 10 of gestation
characteristic manifestation of the disease.
Recurrent hemarthroses
Severe, Factor Lever
≤1% of normal (≤0.01 U/mL)
Factor level
Moderate
Moderate
1%–5% of normal (0.01–0.05 U/mL)
Factor level, mild
6%–40% of normal (0.06–0.40 U/mL)
T/F
tranexamic acid, should be avoided in individuals with hematuria because of the risk of forming clots and producing obstructing clots in the ureter and bladder
T
