Table 1. Intermediate and pathogenic STR expansions identified in ALS, FTD, and control individuals using ExpansionHunter and PCR genotyping.

			ExpansionHunter v4 frequencies						PCR validation frequencies in ALS/FTD
Disease ID	Gene	Expansion type	Control		sALS		sFTD		sALS	sFTD
			n = 4703*		n = 608*		n = 68*
			n	%	n	%	n	%
FTDALS1	C9orf72	Pathogenic	9	0.19	43	7.07	0	0	41	0
HD	HTT	Intermediate	6	0.13	2	0.33	0	0	2	0
SCA1	ATXN1	Pathogenic	5	0.11	1	0.16	0	0	1	0
		Intermediate	564	12	81	13.3	8	11.8	81	8
SCA2	ATXN2	Intermediate	31	0.66	12	1.97	0	0	12	0
SCA8	ATXN8	Pathogenic	40	0.85	5	0.82	0	0	6	0
		Intermediate	35	0.74	2	0.33	1/67	1.49	1	1
SCA17	TBP	Pathogenic	0	0	0	0	1	1.47	0	0
		Intermediate	6	0.13	0	0	0	0	0	1
NIID	NOTCH2NLC	Intermediate	10/4690	0.21	1	0.16	0	0	0	0
FRAXA/ FXTAS	FMR1	Pathogenic	0	0	1/607	0.16	0	0	1†	0
		Intermediate	56/4699	1.19	10/607	1.65	1	1.47	3	0
DM1	DMPK	Pathogenic	1	0.02	1	0.16	0	0	1	0
DM2	CNBP	Pathogenic	0	0	1	0.16	0	0	2	0
		Intermediate	20	0.43	2	0.33	0	0	1	0
Total			783	16.65‡	162	26.64‡	11	16.18‡	152	10

*Total number of control/ALS/FTD individuals unless otherwise stated.

†Individual has both an intermediate and pathogenic STR expansion in FMR1 and has only been included in the pathogenic count.

‡Percentage calculated using the total number of repeat expansions divided by the total number of individuals within that group.