title: Comparison of serum vitamin D level in multiple sclerosis patients, their siblings, and healthy controls.
abstract: BACKGROUND
  Multiple sclerosis (MS) is an autoimmune, neuro-inflammatory disease of central nervous system affecting physical, emotional, and cognitive aspects of patients. Association of vitamin D deficiency and MS has been shown in previous studies. The aim of this study was to evaluate serum vitamin D level in MS cases and their sex-matched healthy siblings (who are genetically near similar) and non-relative sex-matched healthy controls.
  
  
  METHODS
  A total of 135 subjects enrolled in this case-control study. Group one (n = 45) consisted of patients with established MS. Group two (n = 45) included sex-matched healthy siblings of the group one and group three participants (n = 45) were non-relative sex-matched healthy controls. Demographic data (age, sex), level of education, daily sun exposure duration, and month of birth gathered for all. Serum sample of all participants was collected for 25-hydroxy vitamin D measurement.
  
  
  RESULTS
  There was no significant difference between vitamin D level, sun exposure duration, education level, and season of birth in three evaluated groups. Mean vitamin D level was 8.2 ± 10.1 (nmol/l) in women and 13.3 ± 7 (nmol/l) in men (P = 0.001). There was a significant positive correlation between daily sun exposure duration and vitamin D level in whole participants (r = 0.28, P < 0.001) as well as in MS patients (r = 0.32, P = 0.030). Mean vitamin D level was significantly lower in participants who have born in spring and summer.
  
  
  CONCLUSIONS
  Vitamin D deficiency is high among Iranian population as well as MS patients.
authors.affiliation: Brain and Spinal Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ghazaleh
authors.initials: G
authors.lastname: Eskandari
authors.affiliation: Brain and Spinal Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Ghajarzadeh
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mir Saeed
authors.initials: MS
authors.lastname: Yekaninejad
authors.affiliation: MS Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Sahraian
authors.affiliation: Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Razieh
authors.initials: R
authors.lastname: Gorji
authors.affiliation: Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Faezeh
authors.initials: F
authors.lastname: Rajaei
authors.affiliation: Brain and Spinal Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Norouzi-Javidan
authors.affiliation: Department of Neurology, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX.
authors.forename: Alireza
authors.initials: A
authors.lastname: Faridar
authors.affiliation: Brain and Spinal Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Amirreza
authors.initials: A
authors.lastname: Azimi
keywords: Multiple Sclerosis; Population Control; Siblings; Vitamin D