DHCR7 and insomnia: Individuals with SLOS exhibit a range of behavioural symptoms with some overlap with autism, including: hyperactivity, aggression, insomnia, self-injurious behaviour, sensory hypersensitivity and repetitive behaviours [32]; interestingly, several of these behavioural abnormalities are also observed in the 39,XY*O mouse [19,21,22], indicating that hippocampal loss of DHCR7 function may underlie key SLOS phenotypes, and suggesting the 39,XY*O mouse as a potential novel model for aspects of the syndrome.