A 14-year-old boy presents with acute onset of right flank pain, which developed after he helped his father paint the ceiling of his bedroom. Physical examination demonstrates an area of ecchymosis in the right flank that is tender to palpation. The patient has a lifelong history of easy bruising. His brother shows the same tendency. The serum level of clotting factor VIII is less than 2% of normal. Which of the following is the most likely underlying mechanism for bleeding tendency in this patient?
Hemophilia A -X-linked recessive disorder of blood clotting that results in spontaneous bleeding, paicularly into joints, muscles, and internal organs and easy bruising. -Classic hemophilia results from mutations in the gene encoding factor VIII . -Intrinsic Pathway affected -Factor VIIIa complex is the most impoant activator of factor X required for conversion of prothrombin to thrombin.
Circulating antibodies directed against factor VIII
Decreased hepatic synthesis of multiple coagulation factors
Deficiency of vitamin K
Genetic defect involving the factor VIII gene
Bleeding disorder