C9orf72 expansion carriers may have an atypical neuropsychiatric presentation of bvFTD with associated hallucinations or delusions [27, 28], and significantly, family members of C9orf72 carriers have a greater risk of psychiatric disorders including autistic spectrum disorders, psychotic illnesses including schizophrenia, mood disorders and suicide [27]. Here, C9orf72 is linked to autism spectrum disorder.