Building of a Diagnostic/Prognostic Database for Human ERG Variant Effects

Recruiting

• Conditions: Long QT Syndrome

• Registration Number: NCT06087367
• Lead Sponsor: Nantes University Hospital

Brief Summary

Cardiac channelopathies induce severe heart rhythm or conduction disorders. Mutations of the KCNH2 gene, that encodes the human (h) ERG channel, is responsible for 30-40% of all cases of long QT syndrome (inherited LQT2). Besides, hERG is frequently responsible for off-target effects of several pharmacological agents (acquired LQT2). With the advent of Next Generation Sequencing, hundreds of new KCNH2 variants are accumulating in regional databases including those developed by french centers of references. Worldwide, we estimate there are more than 1000 variants for hERG channel. Unfortunately, many of these new variants appear to be of unknown functional significance in spite of available clinical and genetic information. Little is known on whether they affect the channel biophysical properties, its expression at the cell surface and/or its structure. Yet, this information is crucial to determine the real degree of pathogenicity of these variants, and therefore to make the proper diagnosis on inherited LQT2, counsel the patient for his treatment and improve the management of the patient's life. Our ambition is therefore to tackle this issue of variant significance by (i) launching a large-scale multi-functional evaluation of hERG variants, (ii) introducing for the first time a formatted large-scale pathogenicity annotation score for all variants that have been functionally evaluated by this multi-parametric approach, and (iii) regrouping all the relevant information collected in every French Regional centers of reference into a single National database hosted by an infrastructure that possesses enough flexibility for continuous data implementation and cross-referencing. The database will integrate the latest International guidelines for functional pathogenicity annotation. This project will also include the pharmacological characterization of several drugs susceptible to produce acquired LQT2 with variable severities. We aim to understand whether there are structural regions within hERG channel in which the introduction of a variant is more prone to increase the risk of acquired LQT2 or if, on the contrary, a set of variants may relatively protect some patients against LQT2-inducing drugs.

Detailed Description

Not available

Study Timeline

• Study Start: 2021-09-20
• Study First Submitted: 2023-10-12
• Study First Submitted QC: 2023-10-12
• Study First Posted: 2023-10-17
• Primary Completion: 2023-12-31
• Status Verified: 2025-05
• Last Update Submitted: 2025-05-22
• Last Update Posted: 2025-05-23
• Study Completion: 2026-03-24

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 600

Inclusion Criteria

• Patients carrier of a mutation in KCNH2 gene

Exclusion Criteria

• Patients who refuse to take part to research

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
To develop a database listing KCNH2 variants and their clinical impact	42 months	Biophysical and pharmacological characterization; Trafficking impact of hERG variants; Structural impact of hERG variants using modeling tools

Secondary Outcome Measures

Name	Time	Method
To stratify KCNH2 gene variants according to their sensitivity to drugs	42 months	Stratify KCNH2 gene variants according to their sensitivity to drugs known to induce acquired type 2 long QT syndrome

Trial Locations

Locations (2)

Hôpital Bichat - Claude Bernard; 🇫🇷 Paris, France

Nantes university hospital; 🇫🇷 Nantes, Loire-atlantique, France