The amino acid glycine (Gly) plays an important role in neurotransmission. Its action is terminated by rapid re-uptake into the pre-synaptic terminal or surrounding glial cells. This re-uptake is mediated by the sodium- and chloride-dependent glycine transporters 1 and 2 (GLYT1 and GLYT2 respectively) (Broer & Gether 2012, Schweikhard & Ziegler 2012). GLYT2 is encoded by the human gene SLC6A5 and is predominantly expressed in the medulla. Defects in SLC6A5 cause startle disease (STHE or hyperekplexia (HKPX3; MIM:614618)), a neurologic disorder characterised by neonatal hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnea. Sometimes symptoms resolve in the first year of life (Bode & Lynch 2014, James et al. 2012).