title: A gender-specific association of interleukin 1 receptor antagonist polymorphism with schizophrenia susceptibility.
abstract: OBJECTIVE
  Recent genetic studies have revealed that the interleukin (IL) 1 gene complex is associated with schizophrenia in the Caucasian population; however, data from the North African population are limited. To further assess the role of interleukin 1 receptor antagonist protein (IL1Ra) in schizophrenia, we examined a functional multiallelic polymorphism localised in intron 2 of this receptor gene associated with an altered level of IL1Ra.
  
  
  METHODS
  In the present case-control study, we have analysed the (86 bp) n polymorphism of the interleukin 1 receptor antagonist (IL1RN) gene (RS 1794068) by polymerase chain reaction genotyping in 259 patients with schizophrenia and 178 healthy controls from the Tunisian population.
  
  
  RESULTS
  We showed that the frequencies of the IL1RN*2/2 genotype and allele 2 were higher in the patient group compared with the control group, and the difference was statistically significant [13.5% vs. 5.6%, p = 10-3, odds ratio (OR) = 3.2% and 32.8% vs. 21.9%, p = 3 × 10-4, OR = 1.76, respectively). When we evaluated the association between this genetic polymorphism and the clinical variables of schizophrenia, we found that the frequencies of the 2/2 genotype and allele 2 were significantly higher in the male patient group (p = 10-4 and 10-5, respectively) compared with the male control group, indicating a substantially increased risk for sex-onset schizophrenia with inheritance of the IL1RN2 allele. When the association between the genotypes and outcome was evaluated by multiple logistic regression analysis, the adjusted OR for the IL1RN genotypes remained statistically significant [1.39; 95% confidence interval (CI) = 1.11-1.73; p = 0.003].
  
  
  CONCLUSIONS
  The intron 2 polymorphism in IL1RN or a genetic polymorphism at proximity seems to be associated specifically with schizophrenia in the Tunisian male population.
authors.affiliation: 1 Superior Institute of Biotechnology, Monastir University, 5019 Monastir, Tunisia.
authors.forename: Mouna
authors.initials: M
authors.lastname: Ben Nejma
authors.affiliation: 1 Superior Institute of Biotechnology, Monastir University, 5019 Monastir, Tunisia.
authors.forename: Ines
authors.initials: I
authors.lastname: Zaabar
authors.affiliation: 2 Psychosis Vulnerability Laboratory CHU F. Bourguiba, Monastir University, Monastir, Tunisia.
authors.forename: Ferid
authors.initials: F
authors.lastname: Zaafrane
authors.affiliation: 1 Superior Institute of Biotechnology, Monastir University, 5019 Monastir, Tunisia.
authors.forename: Sihem
authors.initials: S
authors.lastname: Thabet
authors.affiliation: 2 Psychosis Vulnerability Laboratory CHU F. Bourguiba, Monastir University, Monastir, Tunisia.
authors.forename: Anouar
authors.initials: A
authors.lastname: Mechri
authors.affiliation: 2 Psychosis Vulnerability Laboratory CHU F. Bourguiba, Monastir University, Monastir, Tunisia.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Gaha
authors.affiliation: 3 Department of Epidemiology and Preventive Medicine, CHU F. Bourguiba, Monastir University, Monastir, Tunisia.
authors.forename: Kamel
authors.initials: K
authors.lastname: Ben Salem
authors.affiliation: 1 Superior Institute of Biotechnology, Monastir University, 5019 Monastir, Tunisia.
authors.forename: Besma
authors.initials: B
authors.lastname: Bel Hadj Jrad