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New lessons from an old gene: complex splicing and a novel cryptic exon in VHL gene cause erythrocytosis and VHL disease

Marion Lenglet, Florence Robriquet, Klaus Schwarz, Carme Camps, Anne Couturier, David Hoogewijs, Alexandre Buffet, Samantha JL. 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 Dr

Key points

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

  • Synonymous mutations in VHL exon 2 may induce exon-skipping and cause familial erythrocytosis or von Hippel-Lindau 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 von Hippel–Lindau disease, which is characterized by the development of highly vascularized tumors. Here, we identified a new VHL cryptic-exon (termed E1’) deep in intron 1 that is naturally expressed in many tissues. More importantly, we identified mutations in E1' in seven families with erythrocytosis (one homozygous case and six compound-heterozygous cases with a mutation in E1' in addition to a mutation in VHL coding sequences) and in one large family with typical VHL disease but without any alteration in the other VHL exons. In this study we have shown that the mutations induced a dysregulation of the VHL splicing with excessive retention of E1’ and are associated with a downregulation of VHL protein expression. In addition, we have demonstrated a pathogenic role for synonymous mutations in VHL-Exon 2 that alter splicing through E2-skipping in five families with erythrocytosis or VHL disease. In all the studied cases, the mutations differentially impact splicing, correlating with phenotype severity. This study demonstrates that cryptic-exon-retention or 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 into the VHL-related-hypoxia-signaling pathway.

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