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  • Comprehensive in silico and functional studies for classification of EPAS1/HIF2A genetic variants identified in patients with erythrocytosis.

Comprehensive in silico and functional studies for classification of EPAS1/HIF2A genetic variants identified in patients with erythrocytosis.

Haematologica (2023-01-27)
Valéna Karaghiannis, Darko Maric, Céline Garrec, Nada Maaziz, Alexandre Buffet, Loïc Schmitt, Vincent Antunes, Fabrice Airaud, Bernard Aral, Amandine Le Roy, Sébastien Corbineau, Lamisse Mansour-Hendili, Valentine Lesieur, Antoine Rimbert, Fabien Laporte, Marine Delamare, Minke Rab, Stéphane Bézieau, Bruno Cassinat, Frédéric Galacteros, Anne-Paule Gimenez-Roqueplo, Nelly Burnichon, Holger Cario, Richard Van Wijk, Celeste Bento, François Girodon, David Hoogewijs, Betty Gardie
ABSTRACT

Gain-of-function mutations in the EPAS1/HIF2A gene have been identified in patients with hereditary erythrocytosis that can be associated with the development of paraganglioma, pheochromocytoma and somatostatinoma. In the present study, we describe a unique european collection of 41 patients and 28 relatives diagnosed with an erythrocytosis associated with a germline genetic variant in EPAS1. In addition we identified 2 infants with severe erythrocytosis associated with a mosaic mutation present in less than 2% of the blood, one of whom later developed a paraganglioma. The aim of this study was to determine the causal role of these genetic variants, to establish pathogenicity, and to identify potential candidates eligible for the new HIF-222inhibitor treatment. Pathogenicity was predicted with in silico tools and the impact of 13 HIF-222variants has been studied by using canonical and real-time reporter luciferase assays. These functional assays consisted of a novel edited vector containing an expanded region of the erythropoietin (EPO) promoter combined with distal regulatory elements which substantially enhanced the HIF-22-dependent induction. Altogether, our studies allowed the classification of 11 mutations as pathogenic in 17 patients and 23 relatives. We described four new mutations (D525G, L526F, G527K, A530S) close to the key proline P531, which broadens the spectrum of mutations involved in erythrocytosis. Notably, we identified patients with only erythrocytosis associated with germline mutations A530S and Y532C previously identified at somatic state in tumors, thereby raising the complexity of the genotype/phenotype correlations. Altogether, this study allows accurate clinical follow-up of patients and opens the possibility of benefiting from HIF-222inhibitor treatment, so far the only targeted treatment in hypoxia-related erythrocytosis disease.

MATERIALS
Product Number
Brand
Product Description

Mouse IgG HRP Linked Whole Ab, Cytiva NA931-1ML
Rabbit IgG HRP Linked Whole Ab, Cytiva NA934-1ML