African-American factor VII-deficient variants in Georgia (FVII variants)

Area of Science:

• Hematology
• Genetics
• Biochemistry

Background:

• Factor VII (FVII) deficiency is a rare bleeding disorder.
• Understanding ethnic-specific variants is crucial for accurate diagnosis.
• Previous studies on African-American FVII variants are limited.

Purpose of the Study:

• To investigate the characteristics of Factor VII-deficient variants and carriers in the African-American population in Georgia.
• To assess Factor VII antigen (FVIIAG) and Factor VII procoagulant (FVIIC) levels in these individuals.
• To evaluate different assay methods for FVIIC measurement.

Main Methods:

• Studied 4 FVII-deficient patients and 3 carriers of African-American descent in Georgia.
• Measured FVII antigen (FVIIAG) using enzyme-linked immunoassay (ELISA).
• Assessed FVII procoagulant activity (FVIIC) via fibrin clotting assays with various thromboplastins (recombinant human, placental, rabbit brain, bovine brain) and an amidolytic method.
• Performed standard prothrombin time (PT) tests.

Main Results:

• Patients and carriers exhibited prolonged PT (18.2 +/- 6.5 sec).
• FVIIAG levels were elevated (73.0 +/- 14.9%).
• FVIIC levels were significantly decreased across all tested methods (HRFVIIC: 30.6%, HPFVIIC: 30.5%, RBFVIIC: 25.3%, BBFVIIC: 30.6%, AMFVIIC: 44.1%).
• Excellent correlation was observed between FVIIC results obtained using human thromboplastins.

Conclusions:

• A subgroup of clinically mild African-American FVII-deficient variants exists in Georgia.
• This variant is characterized by the presence of FVII antigen and reduced FVII procoagulant activity.
• The findings highlight the importance of using appropriate thromboplastins for accurate FVIIC assessment in diverse populations.