 Individuals of Northern European descent are most likely to be affected and estimates of the rates of DH in British and Finnish populations range from 30 in 100,000 to 75 in 100,000 people, respectively.The annual incidence rate of DH in these populations range from 0.8 to 2.7 per 100,000.People of all ages may be affected, although the mean age at diagnosis varies between 30–40 years of age.