A rare inherited coagulation disorder: combined homozygous factor VII and factor X deficiency.
The combined presence in the homozygous state of more than one recessively transmitted coagulation defect may rarely occur in countries with a high rate of consanguinity. In an Iranian family consisting of two parents (second cousins) and two affected siblings, initial phenotypic analysis led to a diagnosis of mild FX deficiency (10-19% FX activity, 42-54% FX:Ag), and genotyping revealed a new homozygous missense mutation in the corresponding gene (Ser3Cys). As both of the sibs had a severe bleeding history that was not compatible with mild deficiency of FX, further phenotypic analysis revealed the additional presence of severe FVII deficiency (<1% FVII activity; 63-111% FVII:Ag) associated with the homozygous missense gene mutation Cys310Phe. In this kindred, lack of identification of the double coagulation defect might have led not only to incomplete understanding of the clinical phenotype but also to an incorrect prenatal diagnosis.
Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, Fondazione Luigi Villa, IRCCS Maggiore Hospital and University of Milan, Milan, Italy. marzia.menegatti@unimi.it
Marzia
M
Menegatti
Mehran
M
Karimi
Isabella
I
Garagiola
PierMannuccio
P
Mannucci
Flora
F
Peyvandi
D000328:Adult; D001778:Blood Coagulation Disorders / Q000175:diagnosis* / Q000235:genetics; D005168:Factor VII Deficiency / Q000150:complications* / Q000175:diagnosis; D005171:Factor X Deficiency / Q000150:complications* / Q000175:diagnosis; D005192:Family Health; D005260:Female; D005838:Genotype; D006720:Homozygote; D006801:Humans; D007492:Iran; D008297:Male; D020125:Mutation, Missense