Haematology

Question 1

What test measures the ability of VWF to bind platelet receptor GPIb?

Answer 1

• VWF:RCo.
• Ristocetin is an antibiotic that is no longer clinically used as it causes platelet aggregation.
• When added to plasma the amount of functional VWF in the plasma that causes platelet agglutination can be quantified.

Question 2

In neonatal alloimmune thrombocytopenia which platelet antigens are antibodies most commonly produced against?

Answer 2

• HPA 1a and 5b.

Question 3

What is the most common cause of familial thrombocytopenia?

Answer 3

• Activated protein C resistance (factor V leiden).
• Point mutation in factor V molecule which prevents inactivation of factor V by activated protein C.
• Leads to procoagulable state.

Question 4

What are features of Schwachman Diamond syndrome?

Answer 4

• Presents in childhood or infancy with exocrine pancreatic insufficiency, short stature, bony abnormalities and cytopaenia.
• Not associated with skin changes and carcinomas.

Question 5

What is dyskeratosis congenita?

Answer 5

• Inherited bone marrow failure syndrome.
• Triad of skin pigmentation, nail dystrophy and oral leukoplakia.
• Usually diagnosed in adulthood or adolescence.

Question 6

What is congenital amegakaryocytic thrombocytopenia?

Answer 6

• Inherited bone marrow failure syndrome.

- Isolated thrombocytopenia that can progress to pancytopenia.

Question 7

What are features of Diamond Blackfan anaemia?

Answer 7

• Mutation in ribosomal genes (ribosomopathy).
• AD 7/1,000,000.
• Profound anaemia 2-6m (90% reconised in 1st year of life).
• 50% have associated congenital abormalities - hypertelorism, snub nose and high arched palate.
• Upper limb and thumb abnormalities.
• Short stature is common.
• RBC’s generally macrocytic.
• High ADA expression differentiates from TEC along with macrocytosis.
• 80% respond to corticosteroids.
• HSCT recommended in <9y transfusion dependent.