title: Sex bias in autism spectrum disorder in neurofibromatosis type 1.
abstract: BACKGROUND
  Despite extensive literature, little is known about the mechanisms underlying sex bias in autism spectrum disorder (ASD). This study investigates the sex differences in ASD associated with neurofibromatosis type 1, a single-gene model of syndromic autism.
  
  
  METHODS
  We analysed data from n = 194 children aged 4-16 years with neurofibromatosis type 1. Sex differences were evaluated across the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS), verbal IQ, Social Responsiveness Scale (SRS) and Conners questionnaires.
  
  
  RESULTS
  There was 2.68:1 male:female ratio in children meeting ASD criteria on the deep phenotyping measures. On symptom profile, males with neurofibromatosis type 1 (NF1) + ASD were more impaired on reciprocal social interaction and communication domains of the ADI-R but we found no differences on the restricted, repetitive behaviours (RRBs) domain of the ADI-R and no differences on the social on the ADOS. NF1 ASD males and females were comparable on verbal IQ, and the inattention/hyperactivity domains of the Conners questionnaire.
  
  
  CONCLUSIONS
  There is a significant male bias in the prevalence of ASD in NF1. The phenotypic profile of NF1 + ASD cases includes greater social communication impairment in males. We discuss the implications of our findings and the rationale for using NF1 as a model for investigating sex bias in idiopathic ASD.
authors: Institute of Brain Behaviour and Mental Health, University of Manchester, Oxford Road, Manchester, M13 9PL UK ; Child and Adolescent Mental Health Service, Royal Manchester Children's Hospital, Oxford Road, Manchester, M13 9WL UK.
authors: Shruti
authors: 0000-0002-4472-4583
authors: S
authors: Garg
authors: Centre for Biostatistics, Institute for Population Health, University of Manchester, Manchester, UK.
authors: Hein
authors: H
authors: Heuvelman
authors: Genomic Medicine, Manchester Academic Health Science Centre, Institute of Human Development, The University of Manchester, Central Manchester University Hospitals NHS Trust, St Mary's Hospital, Oxford Road, Manchester, M13 9WL UK.
authors: Susan
authors: S
authors: Huson
authors: Institute of Brain Behaviour and Mental Health, University of Manchester, Oxford Road, Manchester, M13 9PL UK.
authors: Hannah
authors: H
authors: Tobin
authors: Institute of Brain Behaviour and Mental Health, University of Manchester, Oxford Road, Manchester, M13 9PL UK.
authors: Jonathan
authors: J
authors: Green
keywords: Autism spectrum disorder; Neurofibromatosis type 1; Sex bias; Syndromic autism