SN7
SHORT NOTE
5M
Write a short note on haemophilia.
Definition
Haemophilia = an inherited bleeding disorder caused by deficiency of a coagulation factor, characterised by delayed clotting and prolonged bleeding after trauma.
Types
| Type | Factor deficient | Frequency |
|---|---|---|
| Haemophilia A | Factor VIII | 85% — classical |
| Haemophilia B (Christmas disease) | Factor IX | 14% |
| Haemophilia C | Factor XI | Rare; autosomal, seen in Ashkenazi Jews |
Inheritance
- X-linked recessive (A and B)
- Males are affected; females are carriers
- Affected father → all daughters are carriers, all sons normal
- Carrier mother → 50% of sons affected, 50% of daughters carriers
- About 30% arise from fresh mutation with no family history
Clinical Features
- Haemarthrosis — the hallmark; repeated bleeds into knee, elbow, ankle → deformity and ankylosis
- Deep muscle haematoma
- Prolonged bleeding after circumcision, tooth extraction or minor surgery
- Haematuria, intracranial haemorrhage
- Petechiae are characteristically absent — platelet function is normal
Laboratory Findings
| Test | Result |
|---|---|
| Clotting time | Prolonged |
| APTT | Prolonged |
| Bleeding time | Normal |
| Prothrombin time | Normal |
| Platelet count | Normal |
| Factor VIII assay | Reduced — confirms diagnosis |
- Severity — severe < 1% factor activity; moderate 1–5%; mild 5–25%
Applied Aspects
- Treatment — factor VIII concentrate or recombinant factor; cryoprecipitate; desmopressin in mild haemophilia A
- Avoid aspirin and intramuscular injections
- Formerly a major route of HIV and hepatitis C transmission through pooled plasma products
- Von Willebrand disease — distinguish carefully: autosomal, both sexes affected, bleeding time is prolonged
All questions in Blood (haematology)
- Q1Define erythropoiesis. Describe its sites, stages, and the factors regulating it. Add a note on the fate of red blood cells. ★
- Q2Describe the mechanism of blood coagulation. Explain the intrinsic and extrinsic pathways and the tests used to assess them. Add a note on natural anticoagulants. ★
- Q3Classify blood groups. Describe the ABO and Rh systems and discuss mismatched transfusion reaction. Add a note on erythroblastosis fetalis. ★
- Q4Classify leucocytes and give their normal values. Describe the functions of neutrophils and discuss the types of immunity. ★
- Q5Describe the structure and types of haemoglobin. Outline its synthesis and describe its fate after red cell destruction. ★
- SN1Describe the formation and functions of platelets. ★
- SN2Classify anticoagulants. Describe the mechanism of action of heparin and warfarin. ★
- SN3Define ESR. Give its normal values and enumerate the factors affecting it. ★
- SN4Define anaemia. Classify it morphologically and aetiologically. ★
- SN5Describe bilirubin metabolism. Classify jaundice and give the findings in each type. ★
- SN6Enumerate the plasma proteins with their normal values and describe their functions.
- SN7Write a short note on haemophilia.