Lethal factor VII deficiency due to novel mutations in the F7 promoter: functional analysis reveals disruption of HNF4 binding site

Pharmacogenetic and clinical risk factors for bevacizumab-related gastrointestinal hemorrhage in prostate cancer patients treated on CALGB 90401 (Alliance)

The objective of this study was to discover clinical and pharmacogenetic factors associated with bevacizumab-related gastrointestinal hemorrhage in Cancer and Leukemia Group B (Alliance) 90401. Patients with metastatic castration-resistant prostate cancer received docetaxel and prednisone ± bevacizumab. Patients were genotyped using Illumina HumanHap610-Quad and assessed using cause-specific risk for association between single nucleotide polymorphisms (SNPs) and gastrointestinal hemorrhage. In 1008 patients, grade 2 or higher gastrointestinal hemorrhage occurred in 9.5% and 3.8% of bevacizumab (n = 503) and placebo (n = 505) treated patients, respectively. Bevacizumab (P < 0.001) and age (P = 0.002) were associated with gastrointestinal hemorrhage. In 616 genetically estimated Europeans (n = 314 bevacizumab and n = 302 placebo treated patients), grade 2 or higher gastrointestinal hemorrhage occurred in 9.6% and 2.0% of patients, respectively. One SNP (rs1478947; HR 6.26; 95% CI 3.19-12.28; P = 9.40 × 10-8) surpassed Bonferroni-corrected significance. Grade 2 or higher gastrointestinal hemorrhage rate was 33.3% and 6.2% in bevacizumab-treated patients with the AA/AG and GG genotypes, versus 2.9% and 1.9% in the placebo arm, respectively. Prospective validation of these findings and functional analyses are needed to better understand the genetic contribution to treatment-related gastrointestinal hemorrhage.

Factor VII Deficiency Due to Compound Heterozygosity for the p.Leu13Pro Mutation and a Novel Mutation in the HNF4 Binding Region (-58G>C) in the F7 Promoter

We investigated the molecular basis of factor VII (FVII) deficiency in a Japanese patient and identified compound heterozygous mutations. Factor VII activity and antigen levels in the patient were less than 5.0% and 6.5% of controls, respectively. All exons, exon-intron boundaries, and the 5' promoter region of F7 from genomic DNA were amplified using polymerase chain reaction (PCR). Sequencing analysis of PCR fragments revealed that the patient was heterozygous for a known T to C substitution at nucleotide position 38, which resulted in the p.Leu13Pro missense mutation (Factor VII Morioka) in the signal peptide region, and a novel mutation in the 5' promoter region (-58G>C). An electrophoretic mobility shift assay showed that the mutation in the promoter region reduced the binding of hepatocyte nuclear factor (HNF). It is presumed that the reduced binding of HNF-4 to the F7 promoter region reduces F7 transcription and thus reduces the synthesis and expression of FVII.

Investigation of a common canine factor VII deficiency variant in dogs with unexplained bleeding on autopsy

The factor VII (FVII) protein is an integral component of the extrinsic coagulation pathway. Deleterious variants in the gene encoding this protein can result in factor VII deficiency (FVIID), a bleeding disorder characterized by abnormal (slowed) clotting with a wide range of severity, from asymptomatic to life-threatening. In canids, a single FVIID-associated variant, first described in Beagles, has been observed in 24 breeds and mixed-breed dogs. Because this variant is present in breeds of diverse backgrounds, we hypothesized that it could be a contributing factor to unexplained bleeding observed in some canine autopsy cases. DNA was extracted from paraffin-embedded tissue samples from 67 anticoagulant-negative autopsy cases with unexplained etiology for gross lesions of hemorrhage. Each dog was genotyped for the c.407G>A (F71) variant. Experimental controls included 3 known heterozygotes and 2 known homozygotes for the F71 variant, 2 normal dogs with known homozygous wild-type genotypes (F7WF7W), and 5 dogs with bleeding at autopsy that tested positive for anticoagulant rodenticide and were genotyped as F7WF7W. All 67 cases tested homozygous for the wild-type allele, indicating that the common FVIID variant was not responsible for the observed unexplained bleeding. Our work demonstrates the usefulness of retrospective studies utilizing veterinary diagnostic laboratory databases and tissue archives for genetic studies. In the case of FVIID, our results suggest that a singular molecular test for the F71 variant is not a high-yield addition to postmortem screening in these scenarios.