Population
In our previous study2 we identified all patients registered with Marfan syndrome in Denmark in 1977 to 2014; in total 412 patients, whereof 197 were women (183 above 13 years at end of study). In brief, we verified the Marfan diagnosis after manual evaluation of their medical records and application of the Ghent-II criteria, and listed their civil registration number, given to all Danes at birth2.