Received: 16 November 2020
Accepted: 16 December 2020
First Online: 20 January 2021
Compliance with ethical guidelines
: L.C. Blomaard, B. de Groot, J.A. Lucke, J. de Gelder, A.M. Booijen, J. Gussekloo and S.P. Mooijaart declare that they have no competing interests.
: For this article no studies with human participants or animals were performed by any of the authors. All studies mentioned were in accordance with the ethical standards indicated in each case.