Any neurodevelopmental disorder in which the cause of the disease is a mutation in the SLC12A2 gene. It is characterized by global developmental delay, mild to moderate intellectual disability, delayed, poor or absent speech, hypotonia with delayed or absent walking, bilateral sensorineural deafness, and autistic features. Variable features may include ventricular septal defect, tracheoesophageal fistula, hip dislocation, swallowing difficulties (that may require tube feeding), brain anomalies (including cortical dysplasia and agenesis of the corpus callosum) and spasticity.