[Pycnodysostosis--common ancestor of some Danish patients. Examination and diagnosis based on molecular genetics].

Eight patients with pycnodysostosis from six Danish families were examined for mutations in the cathepsin K gene. Three different mutations are the cause of pycnodysostosis in the six families - five of whom come from Ringkobing County and one from Vejle County. One mutation has a high frequency in the families from Ringkoebing County. The five families are related through a common ancestor, who introduced the mutation around the year 1100. The disease is described with respect to aetiology, symptoms, prognosis, diagnosis, and symptomatic treatment. Research in pycnodysostosis may bring important knowledge to the understanding of related diseases, such as osteoporosis.