<haematology> A haemorrhagic diathesis occurring in two main forms:

1. Haemophilia A (classic haemophilia, factor VIII deficiency), an X linked disorder due to deficiency of coagulation factor VIII.

2. Haemophilia B (factor IX deficiency, Christmas disease), also X linked, due to deficiency of coagulation factor IX.

Both forms are determined by a mutant gene near the telomere of the long arm of the X chromosome (Xq), but a different loci and are characterised by subcutaneous and intramuscular haemorrhages, bleeding from the mouth, gums, lips and tongue, haematuria and haemarthroses.

American spelling: hemophilia

(11 Mar 2008)