Examples for non-matching phenotypes included a child with GDD, mild dysmorphism, and a de novo likely pathogenic variant in NFIX NM_001365902.1:c.273C>A; p.(Phe91Leu) without signs of overgrowth, and a 13-year-old with a homozygous SYNJ1 variant NM_003895.3:c.772C>T; p.(Arg258Trp) and an intermediate atypical phenotype of late childhood-onset epilepsy and mild developmental delay without parkinsonism. The gene discussed is SYNJ1; the disease is Global developmental delay.