| No shunt | Grade 1 | Grade 2 | Grade 3 | Total | |
| Persons | 262 (33.9) | 201 (26.1) | 150 (19.4) | 159 (20.6) | 772 |
| Age years mean±sd | 47.3±15.1 | 44.9±16.1 | 43.7±16.0 | 44.8±14.2 | 45.5±15.4 |
| Sex | |||||
| Females | 146 (32.5) | 113 (25.2) | 79 (17.6) | 111 (24.7) | 449 (58.2) |
| Males | 116 (35.9) | 88 (27.2) | 71 (22.0) | 48 (14.9) | 323 (41.8) |
| HHT | |||||
| Definite | 204 (29.7) | 186 (27.0) | 145 (21.1) | 153 (22.2) | 688 (89.1) |
| Possible | 58 (69.0) | 15 (17.9) | 5 (6.0) | 6 (7.1) | 84 (10.9) |
| Genetic testing | |||||
| HHT1 | 21 (9.4) | 39 (17.4) | 57 (25.4) | 107 (47.8) | 224 (29.0) |
| HHT2 | 145 (47.5) | 104 (34.1) | 38 (12.5) | 18 (5.9) | 305 (39.5) |
| SMAD4 | 1 (10.0) | 4 (40.0) | 2 (20.0) | 3 (30.0) | 10 (1.3) |
| Unknown# | 95 (40.8) | 54 (23.2) | 53 (22.7) | 31 (13.3) | 233 (30.2) |
Data are presented as n (%), unless otherwise stated. HHT: hereditary haemorrhagic telangiectasia. #: unknown family mutation or genetic testing not performed.