SLC6A5 and nervous system disorder: The importance of heteromeric α1β GlyRs in tempering the excitability of motoneurons is evidenced by studies of the rare neurological disorder startle disease/hyperekplexia (Harvey et al., 2008; Schaefer et al., 2022), which is caused by mutations within the corresponding genes: GLRA1 and GLRB (Shiang et al., 1993; Rees et al., 2002), SLC6A5 encoding the presynaptic glycine transporter GlyT2 (Rees et al., 2006; Carta et al., 2012; Giménez et al., 2012) and SLC7A10 encoding Asc-1, an alanine-serine-cysteine transporter (Drehmann et al., 2023).