Table 2.
Frequency of the C9ORF72 repeat expansion in FTD and ALS patient populations
| Familial FTD | Sporadic FTD | Familial ALS | Sporadic ALS | Cases | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Study regiona | Ref. | N | C9ORF72 mutation | N | C9ORF72 mutation | N | C9ORF72 mutation | N | C9ORF72 mutation | excluded h |
| Europe | ||||||||||
| Finland | 28,88 | 27 | 13 (48.1%) | 48 | 9 (18.8%) | 112 | 52 (46.4%) | 289 | 61 (21.1%) | Yes |
| Ireland | 80 | - | - | - | - | 47 | 18 (38.3%) | 386 | 19 (4.9%) | NS |
| UKb | 82 | - | - | - | - | 63 | 27 (42.9%) | 500 | 35 (7.0%) | No |
| UKb | 87 | 93 | 12 (12.9%) | 163 | 6 (3.7%) | - | - | - | - | No |
| UKb | 93 | 161 | 20 (12.4%) | 209 | 16 (7.7%) | - | - | - | - | No |
| Netherlands | 88,92 | 129 | 37 (28.7%) | 224 | 5(2.2%) | - | - | - | - | Yes |
| Belgiumc | 84 | 75 | 12 (16.0%) | 230 | 9 (3.9%) | 15 | 7 (46.7%) | 122 | 6 (4.9%) | Yes |
| France | 88 | 50 | 22 (44.0%) | 150 | 14 (9.3%) | - | - | - | - | |
| Germany | 28,81,88 | 29 | 4(13.8%) | - | - | 69 | 15 (21.7%) | 421 | 22 (5.2%) | Yes |
| Italy (mainland) | 28,81,88,91 | - | - | - | - | 120 | 45 (37.5%) | 1523 | 55 (3.6%) | Yes |
| Italy (Sardinia) | 81,88,91 | - | - | - | - | 21 | 12 (57.1%) | 133 | 9 (6.8%) | Yes |
| Italy (Sicily) | 91 | - | - | - | - | - | - | 101 | 5 (4.9%) | Yes |
| Greece | 89 | - | - | - | - | 10 | 5 (50.0%) | 136 | 11 (8.1%) | NS |
| North America | ||||||||||
| US | 27,78 | 171 | 20 (11.7%) | 203 | 6 (3.0%) | 34 | 8 (23.5%) | 195 | 8 (4.1%) | No |
| USd | 28,88 | - | - | - | - | 163 | 59 (36.2%) | 1014 | 56 (5.5%) | NS |
| Canada | 94 | - | - | - | - | 62 | 17 (27.4%) | 169 | 6 (3.6%) | No |
| Canadae | 27,85 | 26 | 16 (61.5%) | 3 | 0 (0.0%) | - | - | - | - | No |
| USe | 27 | 40 | 9 (22.5%) | 53f | 8 (15.1%) | - | - | - | - | No |
| USe | 79 | 18 | 6 (33.3%) | 6 | 0 (0.0%) | 14 | 6 (42.9%) | 43f | 5 (11.6%) | NS |
| Other regions | ||||||||||
| Israel | 88 | - | - | - | - | 14 | 3 (21.4%) | - | - | NS |
| India | 88 | - | - | 31 | 0 (0.0%) | - | - | 31 | 0 (0.0%) | NS |
| Asiag | 88 | 3 | 2 (66.7%) | 10 | 0 (0.0%) | 20 | 1 (5.0%) | 238 | 0 (0.0%) | NS |
| Guam | 88 | - | - | - | - | - | - | 90 | 0 (0.0%) | NS |
| Australia | 88 | - | - | - | - | - | - | 263 | 14 (5.3%) | NS |
ALS, amyotrophic lateral sclerosis; FTD, frontotemporal dementia; C9ORF72, chromosome 9 open reading frame 72; UK, United Kingdom; US, Unites States.
Only geographical regions with at least 10 FTD or ALS patients are listed.
Cohorts are part of a larger series of UK patients which are grouped in Majounie et al. with highly comparable mutation frequencies.56
Numbers do not include 23 patients with both FTD and ALS of which 85.7% of familial and 6.3% of sporadic patients were C9ORF72 mutation carriers.
In the sporadic ALS cohort, 5.4% (48 of 890) of white and 4.1% (2 of 49) of African American patients carried a C9ORF72 repeat expansion.
Only included patients with a pathological diagnosis of FTLD-TDP.
Includes individuals for which no information on family history was available.
The geographical origin of the Asian patients was not reported in detail; however, the familial ALS patient carrying the C9ORF72 repeat expansion was Japanese.
In studies where cases known to carry mutations in other genes were excluded, the frequency of C9ORF72 repeat expansions are overestimated (NS, not stated).