Mild bleeding diathesis in a boy with combined severe haemophilia B (C(10400)-->T) and heterozygous factor V Leiden.
Haemophilia B patients with factor IX (FIX) activity < 1% are usually characterized by severe bleeding episodes early in life. We report a case of sporadic severe haemophilia B, clinically characterized by mild bleeding diathesis. The presence of anamnestic thrombophlebitis in the patient's mother prompted us to investigate a possible associated hypercoagulable condition. Resistance to activated protein C due to factor V R506Q mutation was present in the mother and in the propositus, in the homozygous and heterozygous form, respectively. Molecular analysis of the FIX gene led to the identification of a nonsense mutation resulting in a stop codon at position 50, previously described and usually responsible for a severe pattern of haemophilia B. The implications of this unusual association are discussed.
Vianello
F
F
Department of Medical and Surgical Sciences, University of Padua Medical School, Italy. fabvian@ux1.unipd.it
Belvini
D
D
Dal Bello
F
F
Tagariello
G
G
Zanon
E
E
Lombardi
A M
AM
Zerbinati
P
P
Girolami
A
A
D020016:Activated Protein C Resistance / Q000097:blood / Q000150:complications* / Q000235:genetics; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005165:Factor V / Q000235:genetics; D005192:Family Health; D002836:Hemophilia B / Q000097:blood / Q000150:complications* / Q000235:genetics*; D006470:Hemorrhage / Q000209:etiology*; D006579:Heterozygote; D006801:Humans; D008297:Male; D017354:Point Mutation; D019851:Thrombophilia / Q000209:etiology
C095381:factor V Leiden; D005165:Factor V