Topic: Disorders of blood and blood cells
Question: A 10 year old boy presented with history of recurrent joint swelling of knees, elbows and ankles, following trivial injuries. His maternal uncle had similar illness. What is the nature of disease and a likely diagnosis which investigations can confirm the disease.
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Hemophilia is a genetic disorder caused by a deficiency of specific blood clotting factors. There are two main types:
• Hemophilia A – Caused by a deficiency of clotting factor VIII and accounts for 80-85% of hemophilia cases.
• Hemophilia B – Caused by a deficiency of clotting factor IX and accounts for the remaining 15-20% of cases.
Hemophilia is caused by a mutation in either the F8 gene (factor VIII) or the F9 gene (factor IX). It is inherited in an X-linked recessive pattern, meaning it is largely observed in males while females are carriers.
Diagnosis of hemophilia involves checking the following:
• Bleeding time: Prolonged bleeding time indicates a coagulation disorder.
• Coagulation factor assays: Specific factor assays for factors VIII and IX reveal deficiency and hemophilia type (A or B).
• Genetic testing: Identifying a mutation in the F8 or F9 gene can confirm diagnosis. This is particularly useful for carrier testing in family members.
• Other coagulation tests: PT, APTT and thrombin time may be abnormal depending on the severity of factor deficiency.
The main clinical manifestations of hemophilia are:
• Easy bruising and prolonged bleeding: Mainly from cuts, wounds and surgical procedures.
• Hemarthrosis: Blood accumulating in joints (knees, elbows, ankles) due to repeated bleeding, causing painful swelling.
• Intracranial hemorrhage: Serious but rare complication seen in severe hemophilia.
The severity of hemophilia depends on the residual clotting factor level – mild (>5%), moderate (1-5%) and severe (<1%). Management focuses on factor replacement therapy and minimizing joint damage.
