ROBO3 is a member of the Roundabout (ROBO) gene family of evolutionarily conserved guidance receptors, which plays crucial roles in axon crossing of the CNS midline. In 2004, pathogenic variants in ROBO3 were first linked to Horizontal Gaze Palsy with Progressive Scoliosis type 1 [HGPPS1 (OMIM # 607313)], an autosomal recessive disorder that is characterized by failure of the corticospinal and somatosensory axon tracts to decussate in the medulla. Hitherto, over 60 ROBO3 pathogenic (or likely pathogenic) variants associated with HGPPS1 have been described in almost 100 patients. With the 20-year milestone, this minireview underscores the growing opportunities to improve the current understanding of the spectrum of HGPPS1 phenotype and ROBO3 genotypes. The increasing need for translational studies that can pave the way for improved clinical management of ROBO3-related disorders is also highlighted.