title: Combined variants in factor VIII and prostaglandin synthase-1 amplify hemorrhage severity across three generations of descendants.
abstract: Essentials Co-existent damaging variants are likely to cause more severe bleeding and may go undiagnosed. We determined pathogenic variants in a three-generational pedigree with excessive bleeding. Bleeding occurred with concurrent variants in prostaglandin synthase-1 (PTGS-1) and factor VIII. The PTGS-1 variant was associated with functional defects in the arachidonic acid pathway.
  
  
  
  Background Inherited human variants that concurrently cause disorders of primary hemostasis and coagulation are uncommon. Nevertheless, rare cases of co-existent damaging variants are likely to cause more severe bleeding and may go undiagnosed. Objective We prospectively sought to determine pathogenic variants in a three-generational pedigree with excessive bleeding. Patients/methods Platelet number, size and light transmission aggregometry to multiple agonists were evaluated in pedigree members. Transmission electron microscopy determined platelet morphology and granule content. Thromboxane release studies and light transmission aggregometry in the presence or absence of prostaglandin G2assessed specific functional defects in the arachidonic acid pathway. Whole exome sequencing (WES) and targeted nucleotide sequence analysis identified potentially deleterious variants. Results Pedigree members with excessive bleeding had impaired platelet aggregation with arachidonic acid, epinephrine and low-dose ADP, as well as reduced platelet thromboxane B2release. Impaired platelet aggregation in response to 2MesADP was rescued with prostaglandin G2, a prostaglandin intermediate downstream of prostaglandin synthase-1 (PTGS-1) that aids in the production of thromboxane. WES identified a non-synonymous variant in the signal peptide of PTGS-1 (rs3842787; c.50C>T; p.Pro17Leu) that completely co-segregated with disease phenotype. A variant in the F8 gene causing hemophilia A (rs28935203; c.5096A>T; p.Y1699F) was also identified. Individuals with both variants had more severe bleeding manifestations than characteristic of mild hemophilia A alone. Conclusion We provide the first report of co-existing variants in both F8 and PTGS-1 genes in a three-generation pedigree. The PTGS-1 variant was associated with specific functional defects in the arachidonic acid pathway and more severe hemorrhage.
authors.affiliation: The Division of Hematology, University of Utah, Salt Lake City, UT, USA.
authors.forename: D
authors.initials: D
authors.lastname: Nance
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Campbell
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.|Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Rowley
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Downie
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.
authors.forename: L B
authors.initials: LB
authors.lastname: Jorde
authors.affiliation: Department of Paediatrics, Division of Haematology/Oncology, University of Toronto, Toronto, ON, Canada.|Program in Cell Biology, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.|Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
authors.forename: W H
authors.initials: WH
authors.lastname: Kahr
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Mereby
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
authors.forename: N D
authors.initials: ND
authors.lastname: Tolley
authors.affiliation: Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Zimmerman
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.|Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Weyrich
authors.affiliation: Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.|Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.|GRECC, George E. Wahlen Salt Lake City VAMC, Salt Lake City, UT, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Rondina
mesh_terms: D000328:Adult; D000368:Aged; D016718:Arachidonic Acid / Q000378:metabolism; D002648:Child; D051545:Cyclooxygenase 1 / Q000235:genetics; D005169:Factor VIII / Q000235:genetics*; D005192:Family Health; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D006470:Hemorrhage / Q000097:blood / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010974:Platelet Aggregation; D010976:Platelet Count; D011446:Prospective Studies; D011451:Prostaglandin-Endoperoxide Synthases / Q000097:blood / Q000235:genetics*; D013929:Thromboxane B2 / Q000235:genetics; D055815:Young Adult
chemical_list: D016718:Arachidonic Acid; D013929:Thromboxane B2; C078147:F8 protein, human; D005169:Factor VIII; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human; D011451:Prostaglandin-Endoperoxide Synthases
keywords: DNA sequencing; bleeding; blood platelet disorder; hemophilia A; platelet aggregation