Carrier detection in hemophilia A: ABO blood group, multiple measurements, and application of logistic discrimination.
In healthy 20- to 50-year-old women, the ABO blood group has a significant effect on levels of von Willebrand factor (VWF:Ag, formerly VIIIR:Ag) and on factor VIII activity (F.VIII:C). However, there is no significant effect of ABO group or subject age on the ratio log e(F.VIII:C/VWF:Ag). Multiple measurements of the "ratio" on possible carriers of hemophilia A may be combined with pedigree information using logistic discrimination to yield final risk assessment. To reduce misclassification of carriers as normal women, a lower limit, specified by the logistic model, is set on the logistic carrier probabilities. In this study, the proportion of blood group A for a population of obligate carriers was significantly higher than that expected for the general population (60% vs. 42%); for a population of control women it was lower than expected (22.5 vs. 42%). The effect for the carriers came primarily from daughters of affected fathers, as 81.3% were of blood group A. These observations indicate that a "universal" discriminant should be applied with caution.
Percy
M E
ME
Department of Obstetrics and Gynaecology, St. Michael's Hospital, Toronto, Canada.
Rusk
A C
AC
Garvey
M B
MB
Freedman
J J
JJ
Teitel
J M
JM
Blake
P
P
Carter
C
C
Andrew
M
M
Johnson
M
M
Inwood
M
M
D000017:ABO Blood-Group System / Q000235:genetics*; D000328:Adult; D000704:Analysis of Variance; D001788:Blood Grouping and Crossmatching; D001800:Blood Specimen Collection; D005169:Factor VIII / Q000032:analysis; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods*; D006467:Hemophilia A / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk
D000017:ABO Blood-Group System; D005169:Factor VIII