Table.

Composition of C9orf72 Discordant ALS Kindreds

Kindred	No. of FDR with ALS	Kindred sizea	p+	Reg ID	C9orf72 status	Phenotype	Age at onset (y)	Survival from onset (mo)	Relationship
A	5	19	0.00000000132553	II.1	Positive	ALS	47	51	Sibling
				II.4	Positive	ALS-FTD	65	16	Sibling
				II.11	Negative	ALS-FTD	59	79	Sibling
B	4	14	0.00000004439112	III.1	Positive	ALS	57	41	Sibling
				III.4	Positive	ALS-ci	60	32	Sibling. Parent of IV.1
				IV.1	Negative	ALS	31	53	Child of III.4
C	2	10	0.00029734114785	IV.1	Positive	ALS-ci	62	18	Sibling
				IV.2	Positive	ALS-ci	74	20	Sibling
				V.3	Negative	ALS	54	16	Cousin
D	4	15	0.00000006037612	II.1	Positive	ALS-FTD	65	25	Sibling
				II.6	Positive	ALS	60	42	Sibling
				II.8	Negative	ALS-FTD	67	23	Sibling
E	2	7	0.00013984608411	IV.6	Positive	ALS	43	36	Sibling
				IV.7	Positive	ALS	60	18	Sibling
				IV.2	Negative	ALS	68	18	Cousin
F	6	13	0.00000000000052	II.6	Positive	ALS-FTD	64	66	Sibling. Child of I.1
				I.1	Negative	ALS-FTD	n/a	n/a	Parent of II.6

Abbreviations: ALS = amyotrophic lateral sclerosis; ci = cognitive impairment (Strong criteria); FDR = first-degree relative; FTD = frontotemporal dementia; n/a = not available.

^aInclusive of first-degree relatives only. + Probability of the exact specified number of first-degree relatives developing ALS within the specified kindred size (inclusive of first-degree relatives only).