This special issue of the Journal of Inherited Metabolic Disease is a collection of articles from the plenary lectures of the SSIEM 2015 Annual Symposium, which took place from September 1 to 4, 2015 in the city of Lyon. This symposium was organized with the support of the French Society for Inborn Errors of Metabolism (SFEIM). The record attendance of 2650 participants, including 121 students and trainees, from 73 countries proved the attractiveness of the scientific programme.

The general theme of the SSIEM Annual Symposium 2015 was “Les Confluences”. It is where Rhône and Saone rivers join in Lyon, but it is also when all health professionals work together and when basic research helps clinicians. The topics were “The Confluence of Research and Inborn Errors of Metabolism”, “New Treatments”, “Antenatal Manifestations of Inborn Errors of Metabolism”, “Disease or not Disease?”, “Riboflavin and Fatty Acid Oxidation” and “Long Term Outcome of Patients with Inborn Errors of Metabolism”. Other areas of inborn errors were covered in 13 workshops with 66 short communications selected from the 900 submitted abstracts, introduced by eight “Update” lectures. The Komrower lecture, given by Bwee Tien Poll-The, was based on her life-long achievements in the field of peroxisomal disorders. The Garrod Award 2015 for the best clinical study in the Journal of Inherited Disease was received by Yanis Trakadis for his update on transcobalamin deficiency (Trakadis et al. 2014). After a breath taking opening ceremony, participants at the Lyon meeting enjoyed during the week a networking dinner in les Subsistances, a monastery built in the seventeenth century, where they could appreciate Lyon cuisine and excellent entertainment.

This event would not have been a success without the commitment of all the members of the Local Organizing Committee, the Scientific Committee, SFEIM, the Council of SSIEM, and the PCO. This success is a guarantee for future events in Lyon.