Whole exome sequencing facilitates early neurodevelopmental diagnosis in an outpatient clinic.

The American College of Medical Genetics and Genomics (ACMG) and other professional organisations recommend whole exome sequencing (WES) as a first-tier genetic test for paediatric patients with congenital anomalies, developmental delay and/or intellectual disability, which has contributed to rapidly increasing rates of genetic testing and diagnosis in this population. We present a case of Rett syndrome diagnosed in early childhood following an atypical presentation of the condition with no regression using WES. This diagnosis was facilitated by a multidisciplinary outpatient neurodevelopmental genetics programme. Non-genetics providers trained in consent for genetic testing allowed for ample access to a comprehensive genetics work-up. The subsequent diagnosis of Rett syndrome qualified this patient for additional resources, novel interventions and family support.