Lack of association or linkage disequilibrium between schizophrenia and polymorphisms in the 5-HT1Dalpha and 5-HT1Dbeta autoreceptor genes: family-based association study

Polymorphisms in the human serotonin receptor 1B (HTR1B) gene are associated with schizophrenia: a case control study

BACKGROUND

Schizophrenia is associated with multiple neurotransmitter disorders, including serotonin (5-hydroxytryptamine, 5-HT). The neuromodulatory action of serotonin on brain function largely depends on the action of specific subtypes of serotonin receptors. The serotonin receptor 1B (HTR1B) gene has been proposed to play putative roles in the development of multiple emotional and psychiatric disorders.

METHODS

To study the relationship of HTR1B polymorphisms and schizophrenia, gene information was drawn from a cohort of 310 schizophrenic patients (152 men and 158 women) and 313 healthy controls (153 men and 160 women) of northern Han Chinese descent. The χ2 test was used to compare allele and genotype distributions between case and control groups. The haplotype and linkage equilibrium were also assessed in two group comparisons.

RESULTS

We detected 14 SNPs. Male patients were observed to have higher frequencies of the A-allele and AA+AG genotype at rs1778258 than female patients (p = 0.012 and p = 0.015, respectively). Both the A-allele and AA+AG genotype were associated with schizophrenia risk (OR = 1.986 and OR = 2.061, respectively), although the statistical significance of the genotype was lost after Bonferroni correction. Linkage analysis showed that rs17273700, rs11568817, rs9361234 and rs58138557 polymorphisms exhibit strong linkage disequilibrium (LD). In addition, schizophrenic patients show stronger linkage between 11,568,817 and rs130058 than healthy controls.

CONCLUSIONS

HTR1B polymorphisms are associated with schizophrenia in the northern Han Chinese population, which provides an etiological reference for schizophrenia.

Cortical serotonin7, 1D and 1F receptors: effects of schizophrenia, suicide and antipsychotic drug treatment

Abnormalities in serotonergic function are thought to be important in the pathology of schizophrenia. Postmortem CNS studies suggest that levels of serotonin receptors may be altered in the cortex of subjects with schizophrenia. Seeking to expand this hypothesis we have examined the effect of schizophrenia and antipsychotic drug treatments on the levels of cortical serotonin7, 1D and 1F receptors. There was a significant decrease in the binding of [3H]SB 269970 to the serotonin7 receptor in Brodmann's area 9 from subjects with schizophrenia compared to controls (Mean+/-S.E.M.: 8.3+/-0.76 vs. 11.0+/-0.64 fmol/mg ETE; p<0.05) and an increase in the binding of that radioligand in the cortex of rats treated with haloperidol (p=0.03). There were no significant differences in [3H]sumatriptan binding to the serotonin1D or serotonin1F receptor in Brodmann's area 9 from subjects with schizophrenia. There was a significant increase in [3H]sumatriptan binding to the serotonin1D in binding Layer 2 from subjects who had potentially died by suicide that was not present in other binding layers or for the serotonin1F or serotonin7 receptors. There was decrease in [3H]sumatriptan binding to the serotonin1D, but not serotonin1F, receptors across all cortical binding layers in rats treated with haloperidol. These data would be consistent with the hypothesis that decreased levels of serotonin7 receptors in Brodmann's area 9 may be involved in the pathological processes of schizophrenia and that levels of cortical serotonin7 and 1D receptors can be affected by antipsychotic drug treatment.

[Lack of association between the G681C polimorphism in the 5-HT1D(beta) autoreceptor gene and schizophrenia]

A major role of the serotonergic system has been hypothesized in the pathogenesis of schizophrenia, mostly based on the evidence of action of atypical antipsychotics. Disturbances of serotonergic pathways have been implicated in the etiology of schizophrenia. The aim of this study was to investigate the association between schizophrenia and the G861C polymorphism in the 5-HT1D(beta) autoreceptor gene. There was conducted a case-control analysis in a sample of 196 schizophrenic patients and 143 gender, age and ethnic matched controls. No statistically differences were found in allelic or genotypic distributions between cases and controls. Thus, the results do not support an association of the G861C polymorphism in the 5-HT1D(beta) autoreceptor gene with schizophrenia in the studied sample.