2. Academic Validation
  3. High-throughput functional mapping of variants in an arrhythmia gene, KCNE1, reveals novel biology

High-throughput functional mapping of variants in an arrhythmia gene, KCNE1, reveals novel biology

  • bioRxiv. 2023 Apr 29:2023.04.28.538612. doi: 10.1101/2023.04.28.538612.
Ayesha Muhammad 1 2,  Maria E Calandranis 3,  Bian Li 3,  Tao Yang 3,  Daniel J Blackwell 3,  M Lorena Harvey 3,  Jeremy E Smith 3,  Ashli E Chew 3,  John A Capra 4,  Kenneth A Matreyek 5,  Douglas M Fowler 6,  Dan M Roden 1 3 7 8,  Andrew M Glazer 1 3
Affiliations

Affiliations

  • 1 Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
  • 2 Medical Scientist Training Program, Vanderbilt University, Nashville, TN 37232, USA.
  • 3 Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
  • 4 Bakar Computational Health Sciences Institute and Department of Epidemiology and Biostatistics, University of California, San Francisco, CA 94143, USA.
  • 5 Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
  • 6 Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
  • 7 Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
  • 8 Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
PMID: 37162834 DOI: 10.1101/2023.04.28.538612
Abstract

Background: KCNE1 encodes a 129-residue cardiac Potassium Channel (IKs) subunit. KCNE1 variants are associated with long QT syndrome and atrial fibrillation. However, most variants have insufficient evidence of clinical consequences and thus limited clinical utility.

Results: Here, we demonstrate the power of variant effect mapping, which couples saturation mutagenesis with high-throughput Sequencing, to ascertain the function of thousands of protein coding KCNE1 variants. We comprehensively assayed KCNE1 variant cell surface expression (2,554/2,709 possible single amino acid variants) and function (2,539 variants). We identified 470 loss-of-surface expression and 588 loss-of-function variants. Out of the 588 loss-of-function variants, only 155 had low cell surface expression. The latter half of the protein is dispensable for protein trafficking but essential for channel function. 22 of the 30 KCNE1 residues (73%) highly intolerant of variation were in predicted close contact with binding partners KCNQ1 or Calmodulin. Our data were highly concordant with gold standard electrophysiological data (ρ = -0.65), population and patient cohorts (32/38 concordant variants), and computational metrics (ρ = -0.55). Our data provide moderate-strength evidence for the ACMG/AMP functional criteria for benign and pathogenic variants.

Conclusions: Comprehensive variant effect maps of KCNE1 can both provide insight into IKs channel biology and help reclassify variants of uncertain significance.

Keywords

KCNE1; long QT syndrome; multiplexed assay of variant effect; saturation mutagenesis; variant classification.

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