Based on his very own needs and difficulties in contacting diagnostic and clinical specialists and discussing with them his own cases where rare metabolic disorders were assumed or had to be treated Renner romantically spent long nightly hours manually searching through treasured paper address lists and notes, some of them hand written and handed-down, wilted and arcane, to send unsolicited snail mail to colleagues and metabolic specialists distributed all over the world inviting them to join in (bolstering the endeavour by posting announcements of Metab-L to Usenet newsgroups). The main impetus - and a main achievement - of the mailing list was to overcome a certain degree of till then almost unavoidable professional isolation encountered in the face of extremely low prevalences and patient numbers in certain inborn metabolic diseases, by means of computer-mediated, group- and community-focused communication.