Deep Mutational Scan of an SCN5A Voltage Sensor

Area of Science:

• Genetics
• Molecular Biology
• Cardiology

Background:

• Traditional methods for studying ion channel gene variants, like patch clamping, are low-throughput.
• Deep mutational scanning offers a complementary, high-throughput approach to assess numerous variants simultaneously.

Purpose of the Study:

• To develop and validate a deep mutational scanning method for SCN5A variants.
• To identify gain- and loss-of-function variants in the SCN5A gene.

Main Methods:

• Created a library of SCN5A variants in the S4 voltage sensor of domain IV.
• Integrated the variant library into HEK293T cells for stable expression.
• Used drug challenge (veratridine, brevetoxin, ouabain) and high-throughput sequencing to assess variant function.

Main Results:

• Identified 40 putative gain-of-function and 33 putative loss-of-function SCN5A variants.
• Drug challenge successfully discriminated wild-type channels from pathogenic variants.
• Patch clamp validation confirmed the accuracy of the deep mutational scan for 8 of 9 tested variants.

Conclusions:

• The developed high-throughput in vitro scan accurately assesses SCN5A variant function.
• This method can effectively identify deleterious variants in SCN5A and other ion channel genes.