Snapshot A 3-year-old boy is seen at his annual pediatrician’s visit with a concern for prolonged nosebleeds. Ever since he was about 2 years old, he has had multiple episodes of nosebleeds that stopped only after hours. On physical exam, his right elbow is slightly swollen and tender to palpation. On further question, there is a family history of unexplained bleeding in the patient’s maternal uncle. Lab results reveal increased PTT that corrects after mixing studies. Introduction Hereditary deficiencies in coagulation factors Hemophilia A and B are clinically indistinguishable Think HIV in older hemophiliacs due to lack of blood screening for HIV with given transfusions Epidemiology Almost exclusively in males Genetics both X-linked recessive etiology Pathogenesis Intrinsic pathway coagulation defects hemophilia A deficiency of factor VIII hemophilia B deficiency of factor IX both lead to inadequate generation of thrombin Presentation Symptoms are similar in both hemophilia A and B spontaneous bleeding or bleeding following trauma or surgery hemoarthroses bleeding into joints easy bruising soft tissue bleeding Physical exam swollen and painful joints bruising studies ↑ PTT corrected with mixing studies indicates a factor deficiency note, if PTT does not correct with mixing studies indicates lupus anticoagulant or factor inhibitor normal PT normal bleeding time most specific test functional assay for factor VIII or IX Differential Diagnosis DIC von Willebrand disease Platelet function disorders Treatment Prevention test carrier status of females with positive family history For mild cases DDAVP for hemophilia A as needed increases endogenous factor VIII Severe cases factor VIII or IX replacement as needed Complications Musculoskeletal complications synovitis arthropathy fractures Prognosis Normal mortality