Table 2.
Incidence data for three subdivisions of primary muscle disorders
| Maximum incidence | Minimum incidence | Average | ||||
|---|---|---|---|---|---|---|
| Type | freq. × 10-6 | fraction | freq. × 10-6 | fraction | ×10-6 | fraction |
| DMD/BMD | 354 | 1/2825 | 186 | 1/5376 | 270 | 1/3703 |
| Other dystrophies | 100 | 1/10000 | 41 | 1/24390 | 70 | 1/14286 |
| Congenital myopathies | 219 | 1/4566 | 100 | 1/10000 | 160 | 1/6250 |
| Total | 673 | 1/1486 | 327 | 1/3050 | 500 | 1/2000 |
DMD mean incidence is well established at 300 × 10-6 (Emery 2002) but data varies from country to country and survey to survey. It is unlikely to be much higher but may be as low as 169 × 10-6 (Cowan 1980). BMD frequency is based on (Emery 1991). Thankfully, both DMD and BMD incidence is probably declining annually due to genetic testing and counselling.
Other dystrophy incidence numbers are scarce to non-existent. The rough estimate maximum is extrapolated from (Bushby 2001) and minimum from (Emery 2002).
Other congenital myopathy numbers are also scarce to non-existent. The maximum estimate is extrapolated from (Nonaka 2001) as 81% of the mean DMD incidence. The minimum estimate is extrapolated from (D'Amico 2008) and (Lopate 2007).
These data were used for estimation of testing cost and should be considered as rough estimates only.