title: Genetic variants of IL-6 and its receptor are not associated with schizophrenia in Taiwan.
abstract: The pathophysiological process of schizophrenia is still unclear. The levels of interleukine-6 (IL-6) and its receptor, soluble IL-6R, have been reported to be elevated in the plasma and cerebrospinal fluid of schizophrenic patients. In this study, we tested the association of genetic variants of IL-6 and IL-6R with schizophrenia. Genotyping of three single nucleotide polymorphisms (SNP) for each IL-6 (IL-6-1, IL-6-2, and IL-6-3) and IL-6R (rs4845617=IL-6R1, rs4553185=IL-6R2, and rs4379670=IL-6R3) gene was performed in 100 patients with schizophrenia and 113 normal controls. The polymorphisms of IL-6R2 were genotyped using Tetra-primer ARMS PCR. IL-6R3 polymorphisms were genotyped using restriction fragment length polymorphism (RFLP) with Apo I enzyme as the restriction enzyme. All other polymorphisms were genotyped using the direct sequencing method. We found a di-nucleotide haplotype block and a tri-nucleotide haplotype block in the genes of IL-6 and IL-6R, respectively. All six SNPs and their haplotypes failed to show a significant association with schizophrenia. The IL-6-2 SNP showed a nominally significant association with the positive symptoms of schizophrenia (p=0.0472). We conclude that the genetic variants of IL-6 and IL-6R are not associated with schizophrenia. In order to verify this result, further study using a larger sample size and exploring the association between the genotype of IL-6-2 and plasma level of IL-6 is recommended.
authors.affiliation: Division of Mental Health and Addiction Medicine, Institute of Population Health Sciences, National Health Research Institute, Miao-Li, Taiwan.
authors.forename: Yu-Li
authors.initials: YL
authors.lastname: Liu
authors.forename: Chih-Min
authors.initials: CM
authors.lastname: Liu
authors.forename: Cathy Shen-Jang
authors.initials: CS
authors.lastname: Fann
authors.forename: Wei Chih
authors.initials: WC
authors.lastname: Yang
authors.forename: Ya-Hui
authors.initials: YH
authors.lastname: Chen
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Tseng
authors.forename: Shih-Kai
authors.initials: SK
authors.lastname: Liu
authors.forename: Ming H
authors.initials: MH
authors.lastname: Hsieh
authors.forename: Tzung-Jeng
authors.initials: TJ
authors.lastname: Hwang
authors.forename: Hung-Yu
authors.initials: HY
authors.lastname: Chan
authors.forename: Jiann-Jyh
authors.initials: JJ
authors.lastname: Chen
authors.forename: Wei J
authors.initials: WJ
authors.lastname: Chen
authors.forename: Hai-Gwo
authors.initials: HG
authors.lastname: Hwu
mesh_terms: D000328:Adult; D044466:Asian People; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D008297:Male; D020641:Polymorphism, Single Nucleotide; D019947:Receptors, Interleukin-6 / Q000235:genetics*; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology; D013624:Taiwan
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6