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Identification of a new VHL exon and complex splicing alterations in familial erythrocytosis or von Hippel-Lindau disease

Marion Lenglet, Florence Robriquet, Klaus Schwarz, Carme Camps, Anne Couturier, David Hoogewijs, Alexandre Buffet, Samantha J. L. Knight, Sophie Gad, Sophie Couvé, Franck Chesnel, Mathilde Pacault, Pierre Lindenbaum, Sylvie Job, Solenne Dumont, Thomas Besnard, Marine Cornec, Helene Dreau, Melissa Pentony, Erika Kvikstad, Sophie Deveaux, Nelly Burnichon, Sophie Ferlicot, Mathias Vilaine, Jean-Michaël Mazzella, Fabrice Airaud, Céline Garrec, Laurence Heidet, Sabine Irtan, Elpis Mantadakis, Karim Bouchireb, Klaus-Michael Debatin, Richard Redon, Stéphane Bezieau, Brigitte Bressac-de Paillerets, Bin Tean Teh, François Girodon, Maria-Luigia Randi, Maria Caterina Putti, Vincent Bours, Richard Van Wijk, Joachim R. Göthert, Antonis Kattamis, Nicolas Janin, Celeste Bento, Jenny C. Taylor, Yannick Arlot-Bonnemains, Stéphane Richard, Anne-Paule Gimenez-Roqueplo, Holger Cario and Betty Gardie

Key Points

  • Mutations in a VHL cryptic exon may be found in patients with familial erythrocytosis or VHL disease.

  • Synonymous mutations in VHL exon 2 may induce exon skipping and cause familial erythrocytosis or VHL disease.

Abstract

Chuvash polycythemia is an autosomal recessive form of erythrocytosis associated with a homozygous p.Arg200Trp mutation in the von Hippel-Lindau (VHL) gene. Since this discovery, additional VHL mutations have been identified in patients with congenital erythrocytosis, in a homozygous or compound-heterozygous state. VHL is a major tumor suppressor gene, mutations in which were first described in patients presenting with VHL disease, which is characterized by the development of highly vascularized tumors. Here, we identify a new VHL cryptic exon (termed E1′) deep in intron 1 that is naturally expressed in many tissues. More importantly, we identify mutations in E1′ in 7 families with erythrocytosis (1 homozygous case and 6 compound-heterozygous cases with a mutation in E1′ in addition to a mutation in VHL coding sequences) and in 1 large family with typical VHL disease but without any alteration in the other VHL exons. In this study, we show that the mutations induced a dysregulation of VHL splicing with excessive retention of E1′ and were associated with a downregulation of VHL protein expression. In addition, we demonstrate a pathogenic role for synonymous mutations in VHL exon 2 that altered splicing through E2-skipping in 5 families with erythrocytosis or VHL disease. In all the studied cases, the mutations differentially affected splicing, correlating with phenotype severity. This study demonstrates that cryptic exon retention and exon skipping are new VHL alterations and reveals a novel complex splicing regulation of the VHL gene. These findings open new avenues for diagnosis and research regarding the VHL-related hypoxia-signaling pathway.

  • Submitted March 9, 2018.
  • Accepted May 23, 2018.
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