SYT1 and Cognitive impairment: A variant in SYT1, with a dominant negative function, has recently been associated with profound cognitive impairment.23 Whilst we observe a copy-number loss and different phenotype, a low haploinsufficiency score is suggestive of adverse functional consequences.24 The participant has a clinical diagnosis of paranoid schizophrenia, a history of alcohol abuse and was a forensic in-patient.