title: Does environmental confounding mask pleiotropic effects of a multiple sclerosis susceptibility variant on vitamin D in psychosis?
abstract: BACKGROUND
  This work addresses the existing and emerging evidence of overlap within the environmental and genetic profiles of multiple sclerosis (MS) and schizophrenia.
  
  
  OBJECTIVE
  To investigate whether a genetic risk factor for MS (rs703842), whose variation is indicative of vitamin D status in the disorder, could also be a determinant of vitamin D status in chronic psychosis patients.
  
  
  METHODS
  A cohort of 224 chronic psychosis cases was phenotyped and biologically profiled. The relationship between rs703842 and physiological vitamin D status in the blood plasma was assessed by logistic regression. Deficiency was defined as a blood plasma concentration below 10 ng/µl. Potential environmental confounders of the vitamin D status were considered as part of the analysis.
  
  
  RESULTS
  We report suggestive evidence of an association with vitamin D status in established psychosis (ß standardized=0.51, P=0.04). The logistic model fit significantly benefited from controlling for body mass index, depression and ethnicity (χ (2)=91.7; 2 degrees of freedom (df); P=1.2×10(20)).
  
  
  CONCLUSIONS
  The results suggest that, in addition to lifestyle changes that accompany the onset of illness, vitamin D dysregulation in psychosis has a genetic component that links into MS. Further, comprehensive studies are needed to evaluate this prospect.
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London, UK.
authors.forename: Conrad O
authors.initials: CO
authors.lastname: Iyegbe
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK; Barts and The London School of Medicine and Dentistry, Queen Mary University, London, UK.
authors.forename: Anita
authors.identifier: 0000-0003-4715-1837
authors.initials: A
authors.lastname: Acharya
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK; National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Lally
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London, UK.
authors.forename: Poonam
authors.initials: P
authors.lastname: Gardner-Sood
authors.affiliation: King's College London Dental Institute, Tower Wing, Guys Hospital , London, UK.
authors.forename: Louise S
authors.initials: LS
authors.lastname: Smith
authors.affiliation: Department of Forensic and Neurodevelopmental Science, Institute of Psychiatry, King's College London.
authors.forename: Shubulade
authors.initials: S
authors.lastname: Smith
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Murray
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Howes
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK; National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK ; Biomedical Research Centre, BRC Nucleus, Maudsley Hospital, South London and Maudsley NHS, London, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Gaughran