epidemiology
Last reviewed 01/2018
Ulnar dysplasia occurs less frequently than radial dysplasia with a quoted ratio of between 1:4 and 1:10. There is an incidence of around 1 in 100,000 to 7 in 100,000. 80% of cases are unilateral in contrast to a tendency to bilateral anomalies with radial dysplasia.
There is a slight male bias. The left side is affected more frequently. 25-50% of all cases are associated with musculoskeletal anomalies but unlike radial dysplasia, there are less syndromic associations.