Pediatric neurotransmitter diseases (PNDs) are recently identified inborn errors of metabolism affecting the central nervous system (CNS). Neurotransmitters such as dopamine, norepinephrine, serotonin and GABA are critical in CNS activities including regulation of body temperature and pain threshold, control of behavior and motor function, neuronal excitation and inhibition, memory, and a host of other processes. PNDs include aromatic L-arnino acid decarboxylase deficiency (ALADD), GTP cyclohydrolase deficiency (Segawa disease or DOPA-responsive dystonia), tyrosine hydroxylase deficiency (THD) and succinic semialdehyde dehydrogenase (SSADH) deficiency (or 4-hydroxybutyric aciduria). Although considered rare, the aggregate incidence of these disorders may be much higher due to a large number of undiagnosed cases. This is because the majority of screening tests used to identify inborn errors of metabolism focus on blood and urine, while the PNDs are often detected only through careful analysis of cerebrospinal fluid (CSF). Only with appropriate testing can the true incidence of the PNDs become clear. Some cases of idiopathic encephalopathy and cerebral palsy have been diagnosed as PNDs. Early diagnosis is vital as irreversible neurologic damage may occur. There are available therapeutic interventions for many of the PNDs, but these cannot be employed without accurate diagnosis. In addition, future genetic counseling relies on the correct differential diagnosis. As research on PNDs is only in its infancy, we feel that a workshop to educate both scientists and lay individuals is timely and important. Attendees will include metabolic specialists, neuroscientists, physicians, nurses and lay community members who have an active interest in the PNDs. Our objectives for the proposed conference include: 1) integration of the most up-to-date information from various research disciplines relevant to the PNDs; 2) overview of testing approaches for identification; 3) identification of promising new avenues for research; 4) fostering of collaborations among researchers in the field (and stimulation of the involvement of new investigators); 5) coordination of approaches to clinical studies and trials; and 6) assessment of the future role of gene therapy and stem cell research in treatment of the PNDs. The perspectives of parents of affected children wilI be an important component of this conference.