Table 1. Variants which are classified as a variant of unknown significance using the adapted ACMG/AMP criteria for DCM. The variants were initially classified as likely pathogenic or pathogenic.

Gene	Number of index patients	Allele	Nucleotide consequencea	Amino acid consequencea	Classification (criteria)b	Previous classification (criteria)c
DSP	1	Heterozygous	c.3383_3384del	Val1128Glyfs*5	VUS (PM2; PP1; PVS1_mod)	Pathogenic (PM2; PP1; PP3; PVS1)
DSP	1	Heterozygous	c.6393del	p.Gly2133Valfs*2	VUS (PM2; PVS1_mod)	Pathogenic (PM2; PP3; PVS1; PP5)
DSP	2	Heterozygous	c.7773_7776del	p.Ser2591Argfs*11	VUS (PM2: PS4_sup; PVS1_mod)	Pathogenic (PM2; PP3; PVS1)
MYH7	1	Heterozygous	c.5722G>A	p.Glu1908Lys	VUS (PM2; PP3)	Likely pathogenic (PM1; PM2; PP1; PP3)
MYH7	1	Heterozygous	c.732+1G>A	Disruptscanonicalsplice site	VUS (PM2; PS4_sup: PVS1_mod)	Likely pathogenic (PM2; PP1; PP3; PP4; PP5)
NEXN	2	Heterozygous	c.1909_1912del	p.Tyr637Alafs*48	VUS (PM2; PP1; PS4_sup)	Likely pathogenic (PM2; PP1; PP3; PP4; PP5)
RBM20	1	Heterozygous	c.1528-1G>C	p.?	VUS (PM2)	Likely pathogenic (PM2; PP1; PP3; PP4; PVS1)
RBM20	1	Heterozygous	c.1764T>G	p.Ile588Met	VUS (PM2)	Likely pathogenic (PM1; PM2; PP3; PP4)
RBM20	1	Heterozygous	c.419del	p.Pro140Argfs*3	VUS (PM2)	Pathogenic (PM2; PP1; PP3; PP4; PVS1)
TNNC1	1	Heterozygous	c.317+1G>A	Disruptscanonicalsplice site	VUS (PM2; PP1_mod; PS4_sup)	Likely pathogenic (PS3; PM2; PP1; PP3;)
TNNT2	5	Heterozygous	c.742T>G	p.Phe248Val	VUS (PM2; PP1; PP3; PS4_sup)	Likely pathogenic (PM1; PM2; PP1; PP3; PP4)
TNNT2	1	Heterozygous	c.442C>T	p.Arg148Trp	VUS (PM2; PM5; PP3)	Likely pathogenic (PM5; PM1; PM2; PP3; PP2)

^aSee Table S1 for the reference refseq transcripts

^bSee Table S7 for full criteria checklist

^cSee Table S8 for the comparison between the previous and adapted classification of all variants that were reclassified from method 2 to method 3