NFIX and neurodevelopmental disorder: Definitive diagnosis of Malan syndrome requires meeting both criteria: (1) ≥2 major clinical features (postnatal overgrowth with height/weight >97th percentile, neurodevelopmental disorders, characteristic craniofacial dysmorphism), and (2) identification of a pathogenic NFIX variant classified as Pathogenic/Likely Pathogenic under ACMG guidelines (Macchiaiolo et al., 2022).