Genetic variants of IL-6 and its receptor are not associated with schizophrenia in Taiwan

Division of Mental Health and Addiction Medicine, Institute of Population Health Sciences, National Health Research Institute, Miao-Li, Taiwan.
Neuroscience Letters (Impact Factor: 2.03). 11/2009; 468(3):330-3. DOI: 10.1016/j.neulet.2009.11.026
Source: PubMed


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.

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Available from: Hsieh H. Ming
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    • "Oh et al. (2014) utilized SNP in IL6R gene, rs4845617 in exon 1 and found it associated with higher allelic transcription (Oh et al., 2014). Liu et al. (2010) analyzed promoter polymorphism − 208A/G (rs4845617) of IL6R gene and found no significant association with schizophrenia in Taiwan (Liu et al., 2010). In our study IL6R rs2228145 and rs4537545 (genotype AC, p = 0,016 and genotype CT, p = 0.048; allele C, p = 0.005 and allele T, p = 0.001; respectively ) were associated with schizophrenia. "
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    ABSTRACT: Schizophrenia has been associated with a large range of autoimmune diseases, with a history of any autoimmune disease being associated with a 45% increase in risk for the illness. The inflammatory system may trigger or modulate the course of schizophrenia through complex mechanisms influencing neurodevelopment, neuroplasticity and neurotransmission. In particular, increases or imbalance in cytokine before birth or during the early stages of life may affect neurodevelopment and produce vulnerability to the disease. A total of 27 polymorphisms of IL1N gene: rs1800587, rs17561; IL1B gene: rs1143634, rs1143643, rs16944, rs4848306, rs1143623, rs1143633, rs1143627; IL1RN gene: rs419598, rs315952, rs9005, rs4251961; IL6 gene: rs1800795, rs1800797; IL6R gene: rs4537545, rs4845617, rs2228145, IL10 gene: rs1800896, rs1800871, rs1800872, rs1800890, rs6676671; IL10RA gene: rs2229113, rs3135932; TGF1B gene: rs1800469, rs1800470; each selected on the basis of molecular evidence for functionality, were investigated in this study. Analysis was performed on a group of 621 patients with diagnosis of schizophrenia and 531 healthy controls in Polish population. An association of rs4848306 in IL1B gene, rs4251961 in IL1RN gene, rs2228145 and rs4537545 in IL6R with schizophrenia have been observed. rs6676671 in IL10 was associated with early age of onset. Strong linkage disequilibrium was observed between analyzed polymorphisms in each gene, except of IL10RA. We observed that haplotypes composed of rs4537545 and rs2228145 in IL6R gene were associated with schizophrenia. Analyses with family history of schizophrenia, other psychiatric disorders and alcohol abuse/dependence did not show any positive findings. Further studies on larger groups along with correlation with circulating protein levels are needed.
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    Full-text · Conference Paper · Oct 2013
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    ABSTRACT: Schizophrenia is a multifactorial disease with changes in immunological system. Such changes are the result of cytokine-level disturbances connected with cytokine gene polymorphisms. However, research about cytokine gene polymorphisms in schizophrenia has been surprisingly limited and ambiguous. The aim of the study was to identify whether polymorphisms of interleukin (IL)-6 and IL-10 are risk factors for the development of paranoid schizophrenia in case-control study. IL-6 (-174G/C; rs 1800795) and IL-10 (-1082G/A; rs 1800896) promoter polymorphisms in patients with paranoid schizophrenia and healthy individuals were genotyped using polymerase chain reaction-restriction fragment length polymorphism method. Differences in IL-6 and IL-10 promoter haplotypes may play an important role in determining the transcription level for IL-6 and IL-10 genes in schizophrenic patients. The presence of allele C at position -174 of IL-6 promoter sequence may correlate with increasing risk of paranoid schizophrenia in the Polish population, but research on a broadened group of people is needed. The presence of allele G at position -1082 of IL-10 promoter sequence correlates with increasing risk of paranoid schizophrenia in the Polish population. The coexistence of genotype GG at position -1082 of IL-10 promoter sequence and genotype GC at position -174 of IL-6 promoter sequence correlates with increasing risk of paranoid schizophrenia in the Polish population.
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