Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.
Funding
Institutional support was provided by the UNCE 204011 and PRVOUK-P24/LF1/3 programs of the Charles University in Prague. KJ and PD were supported by project LM 2010004 BBMRI_CZ and LD by SVV 260148/2015. Dr. Reshma Malviya performed English language editing.