Untangling neurodevelopmental disorders in the adulthood: a movement disorder is the clue.

BACKGROUND: The genetic landscape of neurodevelopmental disorders is constantly expanding and children with early-onset neurological phenotypes increasingly receive a genetic diagnosis. Nonetheless, the awareness of the chronic course of these conditions, and consequently their recognition and management in the adult population, is still limited. RESULTS: Herein, we describe four patients with rare neurodevelopmental disorders (SON, ZMYND11, DNMT1 and YY1-related diseases), who received a genetic assignment only in the adulthood. All these patients had an early developmental delay and displayed a movement disorder (dystonia/ataxia/tremor) which manifested for the first time, or worsened, in the adulthood, prompting the referral to a neurologist. This phenotypic combination led eventually to the genetic testing. We report previously unrecognized features and highlight the peculiarities of the adult presentation of four neurodevelopmental disorders. CONCLUSIONS: This report expands the current knowledge on four rare neurodevelopmental disorders (SON, ZMYND11, DNMT1 and YY1), which was mainly based on reports from paediatric cases. This case series emphasize the importance of a tight neurological surveillance extending beyond the childhood