Haemophilia

Question 1

definition of haemophilia

Answer 1

Bleeding diatheses resulting from an inherited deficiency of a clotting factor.

congenital coagulation disorder

Haemophilia A - most common, deficiency in VIII

B - deficiency in IX (christmas disease)

C - rare, deficiency in XI

Question 2

aetiology of haemophilia

Answer 2

A and B - X linked recessive inheritance

variety of mutations in VIII and IX genes described, 30% are new mutations

factor VIII is a vital co-factor for the intrinsic pathway

activated factor IX converts factor X to Xa (ie activates it)

A - ‘flip tip’ inversion of factor VIII gene in chr 10

Question 3

epidemiology of haemophilia

Answer 3

Incidence of haemophilia A is1in 5–10,000males

haemophilia B is 1 in 25–30,000 males.

Haemophilia C is more common in Ashkenazi Jews.

Question 4

sx of haemophilia

Answer 4

usually benign from childhood, depends on severity - presentation can be early in life or with surgery/trauma

swollen painful joints occuring spontaneously or with minimal trauma - haemarthrosis

painful bleeding into muscles

haematuria

excessive bruising

bleeding after surgery/trauma

female pts often asymptomatic - may have low-enough levels to cause excess bleeding after trauma.

Question 5

signs of haemophilia

Answer 5

bruises

haematomas

haemarthrosis

joint deformity

nerve palsies - nerve compression by haematoma

compartment syndrome - haematoma = increased pressure

signs of IDA

Question 6

Ix for haemophilia

Answer 6

clotting screen - raised APTT (intrinsic and common pathway)

coagulation factor assays - reduced factor VIII, IX, XI depending on condition

other investigations according to complications eg arthroscopy

Question 7

acquired haemophilia

Answer 7

bleeding diathesis causing big mucosal bleeds by suddenly appearing auto-Ab that interfere with factor VIII

Ix - high APPT, high VIII Ab, factor VIII activity <50%