1). Reviewing the research history of RAI1 reveals its intricate association with two rare neurodevelopmental syndromes – Smith–Magenis syndrome (SMS) (OMIM: 182290) and Potocki–Lupski syndrome (PTLS) (OMIM: 610883) – which share overlapping features while also exhibiting distinct, syndrome-specific phenotypes (Refs 2, 3). It has long been recognised that RAI1 is situated within the crucial gene region linked to both SMS and PTLS (Refs 4, 5). Until 2003, Slager et al. (Ref. 6) identified frameshift mutations in RAI1 among SMS patients, confirming the central role of RAI1 in this syndrome. The gene discussed is RAI1; the disease is Smith-Magenis syndrome.