Variability in bleeding phenotype in Amish carriers of haemophilia B with the 31008 C-->T mutation.
The aim of this study was to characterize the variability of bleeding phenotype and its association with plasma factor IX coagulant activity (FIX:C) in haemophilia B carriers in a large Amish pedigree with a unifying genetic mutation, C-to-T transition at base 31008 of the factor IX gene (Xq27.1-27.2). A cross-sectional survey of haemophilia B carriers included a multiple choice questionnaire evaluating symptoms of mucocutaneous bleeding, joint bleeding and bleeding after haemostatic stress [menstruation, postpartum haemorrhage (PPH), dental extractions and invasive surgeries]. Severity of bleeding was graded as 0 to 4, 0 being no bleeding whereas 4 being severe bleeding. Association between total bleeding scores and the FIX:C was evaluated. Sixty-four haemophilia B carriers participated in this study. Median age: 18 years (range 1-70 years); median bleeding score: 1 (range 0-8). Besides PPH, isolated symptoms of bruising, epistaxis, menorrhagia and postsurgical bleeding including dental extraction were not associated with lower FIX:C. Bleeding score >/=3 was associated with involvement of at least two bleeding sites and a lower mean FIX:C of 42 +/- 10.3% (95% CI 36.4-47.7) while a score >3 had involvement of </=2 sites and higher mean FIX:C of 54.9 +/- 21.5% (95% CI 49-61), P = 0.005. Subcutaneous haematoma formation and bleeding after haemostatic stress requiring treatment were associated with bleeding scores >/=3. Phenotypic variability existed among the carriers of haemophilia B who belonged to a single pedigree carrying a single unifying mutation. The utility of bleeding scores to define bleeding phenotype precisely in haemophilia B carriers needs further evaluation.
Sharathkumar
A
A
Indiana Hemophilia and Thrombosis Center, Indianapolis, IN, USA.
Hardesty
B
B
Greist
A
A
Salter
J
J
Kerlin
B
B
Heiman
M
M
Sulkin
M
M
Shapiro
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003288:Contusions / Q000209:etiology / Q000235:genetics; D003430:Cross-Sectional Studies; D004844:Epistaxis / Q000209:etiology / Q000235:genetics; D005164:Factor IX / Q000235:genetics* / Q000378:metabolism; D005260:Female; D002836:Hemophilia B / Q000097:blood / Q000150:complications / Q000235:genetics*; D006470:Hemorrhage / Q000097:blood / Q000209:etiology / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007223:Infant; D008595:Menorrhagia / Q000209:etiology / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D019106:Postoperative Hemorrhage / Q000209:etiology / Q000235:genetics; D012720:Severity of Illness Index; D055815:Young Adult
D005164:Factor IX