Extended Data Table 1.

Sequences of primers, Nanostring probes, and characterized oligomers

Primer/ Identity	Sequence (5–3)
(GGCCCC)5	GGCCCCGGCCCCGGCCCCGGCCCCGGCCCC
(GGGGCC)8	GGGGCCGGGGCCGGGGCCGGGGCCGGGGCCGGGGCCGGGGCCGGGGCC
Intron 3 C9orf72 +	AGATCCGTGTTAAATTTCCTTCC
Intron 3 C9orf72-	CAAAATTATTCTTCCCGAAAAGG
5’ C9orf72-HRE +	GTTTTTCCCACCCTCTCTCC
5’ C9orf72-HRE -	CGACTCCTGAGTTCCAGAGC
45S rRNA forward	GAACGGTGGTGTGTCGTT
45S rRNA reverse	GCGTCTCGTCTCGTCTCACT
28S rRNA forward	AGAGGTAAACGGGTGGGGTC
28S rRNA reverse	GGGGTCGGGAGGAACGG
18S rRNA forward	GATGGTAGTCGCCGTGCC
18S rRNA reverse	GCCTGCTGCCTTCCTTGG
5.8S rRNA forward	ACTCGGCTCGTGCGTC
5.8S rRNA reverse	GCGACGCTCAGACAGG
Spect. forward	AGAACATAGCGTTGCCTTGG
Spect. reverse	TACTGCGCTGTACCAAATGC
GAPDH Nanostring Probe	GGGGAAGGTGAAGGTCGGAGTCAACGGATTTGGTCGTATTGGGCGCCTGGTCACCAGGGCTGCTTTTAACTCTGGTAAAGTGGATATTGTTGCCATCAAT
GUSB Nanostring Probe	CGGTCGTGATGTGGTCTGTGGCCAACGAGCCTGCGTCCCACCTAGAATCTGCTGGCTACTACTTGAAGATGGTGATCGCTCACACCAAATCCTTGGACCC
OAZ1 Nanostring Probe	GGTGGGCGAGGGAATAGTCAGAGGGATCACAATCTTTCAGCTAACTTATTCTACTCCGATGATCGGCTGAATGTAACAGAGGAACTAACGTCCAACGACA
5’ C9orf72-HRE Nanostring Probe	ATAAAGATTAACCAGAAGAAAACAAGGAGGGAAACAACCGCAGCCTGTAGCAAGCTCTGGAACTCAGGAGTCGCGCGCTAGGGGCCGGGGCCGGGGCCGG
Intron 5 C9orf72 Nanostring Probe	AGCCTCTTTCTTCTGTTCTGTTCATAGCACAGTGCCTCATACGCAGTAGGTTATTATTACATGGTAACTGGCTACCCCAACTGATTAGGAAAGAAGTAAA
Spectroscopic DNA/RNA analysis	% of each species when annealed in 100 mM KCI			Calculated melting temperatures
DNA oligonucleotide	Hairpin	Antiparallel G4	Parallel G4	50 mM KCI	100 mM KCI
GGGGCCGGGG	0	0	100	-	79
(GGGGCC)3	25	32	43	-	-
(GGGGCC)4	0	100	0	81	≥91
(GGGGCC)5	10	72	18	-	-
(GGGGCC)6	26	54	20	-	-
(GGGGCC)8	31	61	8	80	-
(GGGGCC)10	26	61	13	-	-
(CCCCGG)4	-	-	-	46	-
RNA oligonucleotide	Hairpin	Antiparallel G4	Parallel G4	50 mM KCI	100 mM KCI
GGGGCCGGGG	0	0	100	-	-
(GGGGCC)4	0	0	100	82	83
(GGGGCC)4-biotin	-	-	-	-	83
(CCCCGG)4	-	-	-	77	-