Nextera rapid capture panel

All procedures were conducted as part of routine clinical care. The study was performed under the ethics guidelines issued by our institution, with written informed consent obtained from all participants for genetic studies.
Genetic analysis for PP genes SCN4A, CACNA1S, and KCNJ2 was performed at the Neurogenetics Unit, National Hospital for Neurology and Neurosurgery as provided by the Channelopathy Highly Specialized National Service for rare disease. Samples underwent next-generation sequencing on an Illumina HiSeq after enrichment with an Illumina custom Nextera Rapid Capture panel (Illumina, Inc, San Diego, CA). For case 2, the library preparation and enrichment were performed with TruSight One kit (Illumina) according to protocol instructions, allowing analysis of a panel of ≈5,000 genes (including PP genes and RYR1). The library was quantified with the Qubit 2.0 Fluorometer system (Thermo Fisher Scientific, Waltham, MA), and 2 × 250-bp paired-end sequencing was performed on the MiSeq sequencer (Illumina), as well as sequences alignment (Burrows-Wheeler aligner) and variant calling (Genome Analysis Toolkit variant caller). The variants were then analyzed with VariantStudio (Illumina).
Additional targeted RYR1 Sanger sequencing of all cases was performed at the Diagnostic DNA Laboratory at Guy's Hospital, London.

DNA was isolated from peripheral blood using standard methods. SCN4A coding regions and exon-intron boundaries were amplified by polymerase chain reaction (PCR). Genetic analysis of ion channel genes SCN4A, CACNA1S, KCNJ2 and CLCN1 was performed at the Neurogenetics Unit, NHNN, as provided by the Channelopathy Highly Specialized National Service for rare diseases. Samples underwent Next-Generation Sequencing on an Illumina HiSeq following enrichment with an Illumina custom Nextera Rapid Capture panel (Illumina, Inc., San Diego, CA).