Lack of Association between the IL6R Gene Asp358Ala Variant (rs2228145), IL-6 Plasma Levels, and Treatment Resistance in Chilean Schizophrenic Patients Treated with Clozapine

High Serum Levels of IL-6 Are Associated with Suicide Attempt but Not with High Lethality Suicide Attempts: A Preliminary Case-Control Study

Suicide attempts are an emerging health problem around the world. Increased levels of IL-6 have been associated with suicidal behavior. Therefore, the aims of this study were to evaluate the serum levels of IL-6 in individuals with suicide attempts and a comparison group and to associate the IL-6 levels with the lethality of the suicide attempt. Additionally, we associated the rs2228145 polymorphism of the IL6R gene with suicide attempts or with the IL-6 serum levels. Suicide attempts and their lethality were evaluated using the Columbia Suicide Severity Rating Scale. The serum concentrations of IL-6 were measured by the ELISA technique in individuals with suicide attempts and then compared to a control group. The rs2228145 polymorphism of the IL6R gene was analyzed by real-time polymerase chain reaction. We found elevated serum levels of IL-6 in the suicide attempt group when compared to the control group (F = 10.37, p = 0.002). However, we found no differences of the IL-6 levels between high and low lethality. The IL6R gene polymorphism rs2479409 was not associated with suicide attempts. Our data suggest that IL-6 serum is increased in individuals with suicide attempts.

Association of the IL-6R gene polymorphic variant rs2228145(C>A) with IL-6 gene polymorphisms in a healthy cohort of Turkish population

The main aim of this study was to investigate the relationship of the carriership of rs2228145 allelic variations of IL-6R with two other allelic variations in IL-6 gene at rs1800795 and rs1800796 loci and with the laboratory data of a healthy cohort of the Turkish population. The data of 121 healthy Turkish subjects (aged 12–84 years) including the past diseases, comorbidities were collected. The laboratory parameters were compared by the frequency of alleles of rs2228145 (C>A). The possible association of polymorphism at rs2228145 locus with the age, gender, and body mass index (BMI) and the frequencies of alleles of rs1800795 and rs1800796 polymorphisms were evaluated. The majority of the subjects had allele A at rs2228145 locus and allele G at rs1800796 locus. The number of white blood cells, platelets, neutrophils and monocytes were significantly higher in the subjects with allele C than those with allele A at rs2228145 locus (P < 0.05). The concentrations of total and direct bilirubin, iron, Sex Hormone Binding Globulin (SHBG) and folic acid of the subjects with allele C were significantly lower than those with allele A (P < 0.05). The uric acid and fasting insulin levels were higher in the subjects with allele C compared with those allele A (P = 0.04). The diversities of the hematological parameters, laboratory findings of liver function tests and renal panel and hormone levels may be explained by the variants of rs2228145 locus at IL-6R gene among healthy Turkish individuals.

Polymorphisms in Schizophrenia-Related Genes Are Potential Predictors of Antipsychotic Treatment Resistance and Refractoriness

BACKGROUND

Approximately 30% of individuals with schizophrenia (SZ) are resistant to conventional antipsychotic drug therapy (AP). Of these, one-third are also resistant to the second-line treatment, clozapine. Treatment resistance and refractoriness are associated with increased morbidity and disability, making timely detection of these issues critical. Variability in treatment responsiveness is partly genetic, but research has yet to identify variants suitable for personalizing antipsychotic prescriptions.

METHODS

We evaluated potential associations between response to AP and candidate gene variants previously linked to SZ or treatment response. Two groups of patients with SZ were evaluated: one receiving clozapine (n = 135) and the other receiving another second-generation AP (n = 61). Single-nucleotide polymorphisms (SNPs) in the genes OXT, OXTR, CNR1, DDC, and DRD2 were analyzed.

RESULTS

Several SNPs were associated with response vs. resistance to AP or clozapine.

CONCLUSIONS

This is the first study of its kind, to our knowledge, in our admixed Chilean population to address the complete treatment response spectrum. We identified SNPs predictive of treatment-resistant SZ in the genes OXT, CNR1, DDC, and DRD2.