Country | Affected (No) | Families (No) | Size of population | Prevalence | Birth incidence | Mutation rate (direct method) (×10−5) | Ascertainment | Reference |
Denmark | 212 | 84 | ∼3 000 000 | ∼1/14150 | NA | NA | Surveys of hospital records and mental institutions | 23 |
USA | 223 | 107 | 743 000 | 1/2500–3300 | 1/2500–3300 | 14–26 | Surveys of hospital records and mental institutions | 24 |
Russia | 124 | 116 | 94 000 | 1/7800 | NA | 4.4–4.9 | Population study of 16 year old youths pre-military exam, and surveys of hospital records | 25 |
Sweden | 74 | 63 | 337 979 | 1/4600 | NA | 4.3 | Population based | 6 |
United Kingdom | 135 | 69 | 668 100 | 1/4150–4950 | 1/2558 | 3.07–5.01 | Population based | 4 |
New Zealand | 52 | 20 | 113 700 | 1/2190 | NA | NA | Population based | 7 |
Italy | 202 | 129 | 2 375 304 | 1/6711 | 1/4292 | 6.5 | Population based | 5 |
Canada | 242 | 82 | 1 500 000 | 1/6198 | NA | NA | Surveys of clinical genetics centres | 26 |
Israel | 390 | NA | 374 440 | 1/960 | NA | NA | Population study of 17 year old youths pre-military exam | 27 |
Present study | 197 | 119 | 733 037 | 1/2983–4436 | 1/2932–3647 | 3.65–5.09 | Population based | Current data |
NA = not analysed.