international working group on neurotransmitter related disorders international working group on neurotransmitter related disorders the international working group on neurotransmitter related disorders is an international collaboration of researchers studying neurotransmitter disorders. it has created a patient registry for longitudinal studies. the group studies deficiencies in aromatic amino acid decarboxylase, tyrosine hydroxylase, dopamine beta-hydroxylase, monoamine oxidase a, dopamine transporter, vesicular monoamine transporter 2 gtp cyclohydrolase (segawa disease), 6-pyruvoyl-tetrahydropterin synthase, dihydropteridine reductase, sepiapterin reductase, folate receptor alpha, dihydrofolate reductase, 3-phosphoglycerate dehydrogenase, 3-phosphoserine phosphatase, phosphoserine aminotransferase, the glycine cleavage system (the deficiency is called glycine encephalopathy or non-ketotic hyperglycinaemia), gaba-transaminase, and succinate-semialdehyde dehydroxylase.