Table 2:

Variant analysis for our cases

Category		Case 1	Case 2	Case 3	Case 4 (deceased)
Genetic screening method		trio; WGS	trio; WES	trio; targeted sequencing	Singleton; targeted sequencing
Variant		chr2:241723210G>T; c.744C>A; p.(Asp248Glu)	chr2:241727557A>G; c.274T>C; p.(Cys92Arg)	chr2:241715312G>A; c.914C>T; p.(Pro305Leu)	chr2:241727535G>A; c.296C>T; (Thr99Met)
Zygosity		Heterozygous	Heterozygous	Heterozygous	Heterozygous
Segregation		de novo	de novo	de novo	de novo
Conserved site		Yes	Yes	Yes	Yes
Novel or reported		Novel	Novel	Reported	Reported
Affected exon		Exon 8	Exon 4	Exon 11	Exon 4
Amino acid change (Grantham distance)		Minor (score: 45)	Major (score: 180)	Minor (score: 98)	Minor (score: 81)
population database (gnomAD)		No	No	No	No
Location of variant		Motor domain	Motor domain	Motor domain	Motor domain
in silico tools	Mutation Taster#	Disease causing (p=0.999)	Disease causing (0.999)	Disease causing (0.999)	Disease causing (0.999)
	PolyPhen-2##	Probably damaging (p=0.998)	Probably damaging (p=1.0)	Probably damaging (p=1.0)	Probably damaging (p=1.0)
	SIFT###	Damaging (score = 0.001)	Damaging (score = 0.000)	Damaging (score = 0.001)	Damaging (score = 0.000)
ClinVar		No	No	Yes	Yes
ACMG classification		Likely pathogenic	Likely pathogenic	Likely pathogenic	Likely pathogenic

RefSeq ID: NM_001244008.1 (longest isoform): Position: GRCh37 chr2:241,653,181–241,759,725, size: 106,545 and total exon count: 49; NCBI Protein ID: NP_001230937.1 (longest isoform); Ensembl transcript ID: ENST00000320389. WGS = whole genome sequencing, WES = whole exome sequencing, ACMG= American College of Medical Genetics, gnomAD = Genome Aggregation Database.

^#: v2.0. URL = www.mutationtaster.org/

^##: v2.2.2r398. URL = http://genetics.bwh.harvard.edu/pph2/. Score range: 0.0 (tolerated) to 1.0 (deleterious)

^###: v6.2.1. URL = http://sift.jcvi.org/. Score range: 0.0 (deleterious) to 1.0 (benign). Prediction cut-off = 0.05.