*2.3. Mutation Screening*

DNA was obtained from the peripheral blood by phenol extraction or the salting-out method. Direct Sanger sequencing of twelve *LMNA* exons (canonical transcript NM\_170707.4) including flanking intronic regions was performed in 16 probands as described previously [15]. In one case, it was followed by multiplex ligation-dependent probe amplification (MRC Holland, Amsterdam, Netherlands) [18]. In 5 probands, next generation sequencing (NGS) was performed. Libraries were prepared using an Illumina: TruSeq Exome Enrichment Kit for whole exome sequencing (WES) in 1 proband, Nextera Rapid Capture Exome Library Kit with different enrichment probes for TruSight One (TSO) gene panels in 2 probands and TruSight Cardio (TSC) Sequencing Kit in 2 probands (Illumina, San Diego, CA, USA). WES and TSO libraries were sequenced on Illumina HiSeq1500 and TSC on Illumina MiSeq. Library preparation, sequencing, and data analysis were performed as described previously [19]. Variants identified in probands were followed up by Sanger sequencing of relatives' DNA using BigDye Terminator v3.1/v1.1 Cycle Sequencing Kit (Life Technologies) according to the

manufacturer's instructions and the 3500xL/3130xL Genetic Analyzer (Life Technologies, Carlsbad, CA, USA). The results were analysed with Variant Reporter 1.1 Software (Life Technologies). Non-missense mutations included insertions, deletions, nonsense mutations, or mutations affecting splicing.
