SLC6A1 and Neurodevelopmental delay: The draft conceptual model of SLC6A1-NDD will likely be very similar to that of many other neurodevelopmental disorders, such as Angelman syndrome (Willgoss et al., 2020) and STXBP1-Related Disorder (Sullivan et al., 2022), with only a few distinguishing domains, such as the presence of cognitive regression, and the idiosyncratic hand use described by KOLs as the first noticeable symptom of the disorder.