A boy presents with bleeding gums and swollen joints accompanied by bleeding into the joints. Both his paternal and maternal uncles have similar symptoms. Which clotting factor deficiency is most likely responsible?

Explanation

The symptoms of bleeding gums and hemarthrosis in multiple male relatives on both sides suggest a deficiency of Factor VIII, which is characteristic of Hemophilia A. Factor IX deficiency causes Hemophilia B, while deficiencies in Factors X and VI present differently.