HY USMLE Q #765 – Hematology

A 15-year-old girl comes to the physician for recurrent nosebleeds and heavy menses. Her father also has history of nosebleeds. Laboratory studies show:

Hemoglobin                                                                      12 g/dL
Platelets                                                                              400,000/μL
Bleeding time                                                                   8 minutes
Prothrombin time                                                         12 seconds
Partial thromboplastin time                                   38 seconds

Which of the following is the most likely explanation for these findings?

  Antibodies against glycoproteins IIb/IIIa
  Deficiency of clotting factor
  Deficiency of bridging molecule
  Inability to cleave von Willebrand factor multimers
  Reduction in erythrocyte spectrin