Genome Editing of Induced Pluripotent Stem Cells to Decipher Cardiac Channelopathy Variant

Area of Science:

• Cardiovascular Genetics
• Stem Cell Biology
• Molecular Cardiology

Background:

• Long QT Syndrome (LQTS) is a genetic disorder causing dangerous heart rhythms and sudden death.
• Genetic testing for LQTS often identifies Variants of Uncertain Significance (VUS), hindering diagnosis.
• Accurate pathogenicity assessment of VUS is crucial for clinical management.

Observation:

• Patient-specific induced pluripotent stem cells (iPSCs) were generated from a KCNH2 (LQT2) gene variant carrier.
• iPSC-derived cardiomyocytes (iPSC-CMs) carrying the T983I VUS showed prolonged action potential duration and reduced potassium current.
• These VUS iPSC-CMs exhibited increased susceptibility to proarrhythmia when exposed to torsadogenic drugs.

Findings:

• Genome editing using CRISPR/Cas9 normalized the cellular phenotype in VUS iPSC-CMs.
• Introducing the homozygous variant into healthy iPSC-CMs replicated LQTS-like cellular defects.
• The KCNH2 T983I variant demonstrated a potentially pathogenic effect on cardiac electrophysiology.

Implications:

• Genome editing of iPSCs is a powerful tool for functional VUS assessment in cardiac channelopathies.
• This methodology can reclassify VUS, improving diagnostic accuracy for LQTS.
• Findings support classifying the KCNH2 T983I variant as potentially pathogenic, guiding clinical decisions.