. 2023 Nov 30;9(6):e200109. doi: 10.1212/NXG.0000000000200109

Table 2.

Pooled Proportion of ALS Cases That Are Familial (fALS), According to Geographic Region and Family History Criteria Used to Define fALS, Among Population-Based Studies

Degree of ALS-affected relative used to define fALS	Population-based studies	fALS cases	Total ALS	Estimate (lower limit, upper limit)
Europe
First-degree	4	18	424	0.05 (0.03, 0.07)^a
First or second-degree	3	16	194	0.09 (0.05, 0.15)^a
First or second-degree or more distant	1	50	444	0.11 (NA, NA)
North America
First-degree	4	324	6,985	0.05 (0.04, 0.05)^a
First or second-degree	1	49	946	0.05 (NA, NA)
First or second-degree or more distant	0	NA	NA	NA
Overall
First-degree	9	344	7,512	0.05 (0.04, 0.05)^a
First or second-degree	4	65	1,140	0.07 (0.04, 0.11)^a
First or second-degree or more distant	1	50	444	0.11 (NA, NA)

Abbreviation: ALS = amyotrophic lateral sclerosis; NA = not applicable.

Random-effects meta-analytic estimates and corresponding 95% confidence intervals are presented (>2 and I² < 90%). Otherwise, weighted averages and ranges are presented.