Genotype-Phenotype Relationship among 785 Unrelated White Women with Inherited Congenital Factor VII Deficiency: A Three-Center Database Study.

BACKGROUND

Congenital factor VII (FVII) deficiency, a rare bleeding disorder resulting from mutations in the F7 gene with autosomal recessive inheritance, exhibits clinical heterogeneity that lacks a strong correlation with FVII:C levels. The objective of this study was to discern genetic defects and assess their associations with the clinical phenotype in a substantial cohort comprising 785 white women exhibiting FVII:C levels below the age-dependent cut-off percentage.

PATIENTS AND METHODS

Individuals with verified inherited factor VII deficiency underwent i) genotyping using the Sanger method and multiplex ligation-dependent probe amplification (MLPA) to identify F7 mutations, including common polymorphic variants. Additionally, they were ii) categorized based on clinical bleeding scores (BS). Thrombophilic variants and blood groups were also determined in the study participants.

RESULTS

The probands in this study encompassed both asymptomatic individuals (referred for a laboratory investigation due to recurrent prolonged prothrombin time; n = 221) and patients who manifested mild, moderate, or severe bleeding episodes (n = 564). The spectrum of bleeding symptoms included epistaxis, gum bleeding, gastrointestinal bleeding, hematuria, postoperative bleeding, and gynecologic hemorrhage. The median ISTH bleeding score (BS) recorded within a two-year period prior to the work-up was 2 (0-17). Notably, this score was significantly higher in symptomatic women compared to their asymptomatic counterparts (3 versus 0; < 0.001). The corresponding PBAC score before hormonal treatment stood at 225 (5-1200), exhibiting a positive correlation with the ISTH BS (rho = 0.38; = 0.001). Blood group O was more prevalent in symptomatic women compared to asymptomatic individuals (58 versus 42%; = 0.01). Among the 329 women (42%), known and novel mutations in the F7 gene, encompassing coding regions, exon/intron boundaries, and the promoter region, were identified, while common polymorphisms were detected in 647 subjects (95%). Logistic regression analysis, adjusted for clinical and laboratory data (including blood group, FVII activity, the presence of F7 gene mutations and/or polymorphisms, thrombophilia status, and additional factor deficiencies) revealed that older age at referral (increase per year) (odds/95% CI: 1.02/1.007-1.03), the presence of blood group O (odds/95% CI: 1.9/1.2-3.3), and the coexistence of further bleeding defects (odds/95% CI: 1.8/1.03-3.1) partially account for the differences in the clinical bleeding phenotype associated with FVII deficiency.

CONCLUSION

The clinical phenotype in individuals with FVII deficiency is impacted by factors such as age, blood group, and the concurrent presence of other bleeding defects.