Congenital deficiencies of Factors VIII and IX (Hemophilia A and B, respectively) are X-linked recessive disorders that almost always affect males. Rarely a female may have hemophilia.
genotypic male, phenotypic female
demonstrate Y chromosome
XO on cytogenetics, heterozygous for defective X chromosome on genetic analysis
homozygous for defective X chromosomes
consanguinity, family history of hemophilia in the families of both parents, demonstrate homozygous on genetic analysis
lyonization with inactivation of normal X chromosome, allowing the defective X chromosome to be active
demonstrate heterozygous on genetic analysis
presence of a Factor VIII or IX inhibitor
failure of normal plasma to correct the aPTT
other severe coagulation factor defect with hemarthroses
deficiency in Factor V, VII or X
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Specialty: Hematology Oncology, Clinical Laboratory