With the onset of seizures, development may slow and in some cases children loose developmental skills during the cluster of seizures. Approximately 70% of individuals with PCDH19-related epilepsy ultimately end up with a degree of intellectual disability ranging from mild to profound. Other neurodevelopmental disorders are common, most frequently autism spectrum disorder (ASD) and behavioural difficulties; later onset psychosis (when understanding of reality is altered so that people can see, hear and/or believe things as real when they are not) occurs in approximately 20% of females (Vlaskamp 2019). These cognitive and behavioural conditions can have a significant impact on the quality of life for people with PCDH19-related epilepsy and their families.