Congenital coagulation factor VII deficiency: A phenotype and genotypestudy in Taiwan

Introduction:Congenital factor VII (FVII) deficiency is a rare coagulation disorderinherited by autosomal recessive pattern with an estimated incidence of 1/500,000 inthe general population. Its clinical and genetic studies in Asian countries are relativelylimited than those from the West.Materials and methods:From January 2009 to September 2013, there were 7unrelated patients (4 men and 3 women) with congenital factor VII deficiencydiagnosed and enrolled in this study. Their clinical manifestations, prothrombin time(PT), FVII coagulation activity and causative mutation of FVII gene were analyzed.All exons of FVII gene were amplified using polymerase chain reaction and followedby direct sequence.Results:Their average age was 46 years old, with a range of 23 to 80. The clinicalsymptoms of this cohort varied markedly, including no symptom (n=2), easybruising, epistaxis, menorrahgia, prolonged bleeding after injury and spontaneous life-threatening gastrointestinal bleeding (n=3). The median time of PT was 46 sec,ranging from 16.2 to 92.4 sec. The median coagulatioon FVII activity was 7.2%,ranging from 0.6% to 21.8%. There was no correlation between the circulating FVIIactivity and the clinical bleeding manifestations. Compound heterozygous andhomozygous mutations were detected in each three patients, respectively and the restof one patient was found to have only heterozygous mutation in one allele. Two ofthe 3 patients with homozygous mutation were found to have double homozygousmutations. Exons 7, 8 and 4 encoded gene mutations were more commonly found.Conclusion:FVII coagulation activity did not correlate with clinical bleedingsymptoms. The most common genetic defects were compound heterozygous andhomozygous mutation. More patients are needed to investigate further whether thereare racial differences in genotypes and phenotypes of congenital FVII deficiencybetween Asian and the western countries.