Neurocognitive follow-up in adult siblings with Phelan-McDermid syndrome due to a novel SHANK3 splicing site mutation.

The long-term observations are sparse in PMD and SHANK3 mutations. This is the neurocognitive follow-up from childhood to middle ages, where a sharp neurocognitive decline was observed. We conclude that progressive neuropsychiatric symptoms in adolescence are a universal clinical clue for PMD diagnosis and an underlying SHANK3 splicing site mutation.