In 2013 the initiative “International Working Group on Neurotransmitter Related Disorders (iNTD)” was founded. The major goal of Network I is to set-up a web-based patient registry for inherited defects of biogenic amines, pterin, folate, serine, glycine and GABA metabolism. It includes 42 scientific and clinical partners from 26 countries. This aims to provide a basis for improving our understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases, their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies. Based on the evaluation of current known diagnostic and therapeutic strategies, consensus care guidelines will be developed.