Analysis of Phenotype and Genotypein an Inherited Coagulation Factor VII Deficiency Pedigree

To identify potential mutations and analyze the phenotype in an inherited factor VII (FVII) deficiency pedigree.

Prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, FVII activity (FVII:C), FVII antigen (FVII:Ag) and other coagulant parameters of the proband and family members were measured. Calibrated automated thrombin generation measurements were used to detect coagulation status. All the exons, exonintron boundaries and 5', 3' untranslated sequences of the F7 gene in the proband and other family members were amplified by polymerase chain reaction (PCR). The PCR products were screened by direct sequencing. The detected mutations were confirmed by sequencing the other strand and analyzed by PIC software.

The PT in the proband was prolonged and further study showed that the FVII:C and FVII:Ag were below the normal range, 3% and 38%, respectively. Double heterozygous mutations in the proband were identified: an A to G mutation at position 11,459 in exon 8, resulting in a p.Lys341Glu substitution, and a 2bp deletion (nt 27 del CT) mutation in exon 1a, leading to a frameshift and the creation of a premature stop codon. Both endogenous thrombin potential (ETP) and peak height in the proband were declined. Her father, brother, daughter, son, and niece were heterozygous for the nt 27 del CT mutation, while her mother, little brother, little niece, and little nephew were heterozygous for the Lys341Glu mutation, and their ETP and peak height obtained more than half normal ETP and peak height, respectively. Model analysis indicated that the Lys341Glu mutation will interrupt the electrovalent bond between 341Lys and 289Asp.

Compound heterozygous mutations (p.Lys341Glu and nt27 del CT) which were responsible for the bleeding tendency were found in a pedigree of inherited FVII deficiency. The Lys341Glu mutation is firstly reported and nt27 del CT may be one of the mutational spots in Chinese population.