Clozapine-induced weight gain associated with the 5HT2C receptor -759C/T polymorphism.

Weight gain has been documented as a significant adverse effect associated with many of the atypical antipsychotic medications. Several recent reports have linked a -759C/T polymorphism of the 5HT2C receptor gene and obesity as well as chlorpromazine, risperidone, and clozapine induced to weight gain. This aim was to determine the association between changes in body mass index (BMI) during clozapine treatment and the -759C/T polymorphism of the 5HT2C receptor gene. This study included 41 patients with treatment-refractory schizophrenia (DSM-IV) who were followed prospectively during treatment with clozapine. Weight and height measurements were obtained prior to starting clozapine and after 6-months of treatment. Genomic DNA was isolated from a whole blood sample and analyzed for the -759C/T polymorphism of the 5HT2C receptor gene. A chi(2) analysis comparing whether or not the subjects carried a -759T allele in subjects grouped as having an increase of more or less than 7% of their baseline BMI during treatment with clozapine found that the presence of the -759T allele was significantly higher in subjects with less than or equal to a 7% increase in baseline BMI compared to those with a greater than 7% increase in BMI. A multiple linear regression analysis showed that both baseline BMI and the presence or absence of the -759T allele had significant effects on 6-month BMI. The T allele may have a protective function in preventing significant weight gain from clozapine. Subjects without the -759T variant allele were at a greater risk for weight gain from clozapine over 6-months compared to those with the -759T allele.     

Weight gain associated with the -759C/T polymorphism of the 5HT2C receptor and olanzapine.

BACKGROUND: Weight gain from atypical antipsychotic use has become a significant problem. Recent reports have liked the -759 polymorphism of the 5HT2C receptor and obesity as well as weight gain from chlorpromazine, risperidone, and clozapine. AIM: To determine associations between weight gain during olanzapine treatment and the -759C/T polymorphism of the 5HT2C receptor gene. METHODS: This study included 42 acutely ill patients with schizophrenia (DSM-IV). Weekly assessments included Brief Psychiatric Rating Scale (BPRS), Scale for Assessment of Negative Symptoms (SANS), and weight measurements. Olanzapine was titrated to a fixed dose (7.5-20 mg/day) for 2-6 weeks. A 24 hr plasma level was obtained at the endpoint visit. Genomic DNA was isolated from a whole blood sample and analyzed for the -759C/T polymorphism of the 5HT2C receptor. RESULTS: A chi-square analysis was conducted comparing the distribution of T and C alleles in subjects grouped as gaining more or less than 5, 7, and 10% of their baseline weight during treatment with olanzapine. A threshold of 10% was found to be significant. The distribution of T alleles was higher in subjects not gaining 10% of more of their body weight compared who did gain significant weight (11/27 (40.7%) vs. 0/15 (100%), chi2 = 11.805, P = 0.0035). CONCLUSIONS: Subjects with a T allele of the 5HT2C receptor -759C/T polymorphism may have a lower incidence of weight gain from olanzapine over a 6 week period compared to those with the C allele. These results need to be replicated.     

Distribution of the serotonin 2C (5HT2C) receptor gene -759C/T polymorphism in patients with schizophrenia and normal controls

BACKGROUND: In patients with schizophrenia, the percentage of patients with diabetes has been found to be twice that of the normal population. The risk factors for this higher rate are unknown, although dietary, lifestyle, and genetic factors have all been suggested. Recently, a polymorphism (-759C/T) in the serotonin 2C (5HT2C) receptor promoter region has been associated with the development of diabetes in a normal control population, with the frequency of the T allele being higher in subjects without diabetes. AIM: To determine whether the distribution of the -759C/T polymorphism of the 5HT2C receptor is different among patients with schizophrenia and normal controls. METHODS: DNA from 100 patients with schizophrenia and 81 normal controls were analyzed for the 5HT2C receptor -759C/T polymorphism to determine its allelic frequencies in these two groups. RESULTS: Using a chi-squared analysis, no statistical differences in the distribution of C alleles and T alleles were found between the two groups (P=0.2931). CONCLUSIONS: Patients with schizophrenia have a higher risk for developing diabetes than the general population. We did not find a higher distribution of the -759T allele of the 5HT2C receptor in normal controls compared with in patients with schizophrenia. This suggests the higher prevalence of diabetes in schizophrenia is not due to this polymorphism.     

Negative association between T102C polymorphism at the 5-HT2A receptor gene and bipolar affective disorders in Singaporean Chinese

BACKGROUND: Serotonergic system abnormalities have been implicated in the pathogenesis of bipolar affective disorders. The 5-hydroxytryptamine type 2A (5HTR2A) receptor gene located on chromosome 13 (13q14-21) can be considered as a candidate gene for bipolar affective disorder (BPAD). METHODS: Seventy-two patients with BPAD and 74 normal population controls were genotyped with restriction fragment length polymorphism (RFLP) in the 5HTR2A receptor gene. RESULTS: We report a negative association between 5HTR2A receptor gene and BPAD. The association was examined using a case-control design. Allele and genotype frequencies as well as homozygote-heterozygote distribution at the 5HTR2A receptor gene polymorphism were compared between the two groups. There were no significant differences in the allelic or genotype frequencies and the homozygote-heterozygote distributions. Limitations: Patients were recruited from one hospital in Singapore. The case-control study design needs replication. CONCLUSION: Our finding indicates that the 5HTR2A receptor gene polymorphism is not a major factor in the genetic susceptibility to BPAD in Singaporean Chinese.     

5-HTR2A基因启动子区-1438G/A多态性与抗精神病药源性肥胖的核心家系关联研究

目的探讨中国汉族首发精神分裂症(schizophrenia,SCH)患者抗精神病药物(antipsychoticagents,APS)治疗过程中体重增加是否与五羟色胺2A受体(5-hydroxytryptamine2Areceptor,5-HTR2A)基因启动区-1438G/A多态性相关。方法对84例首发精神分裂症患者(包含完整核心家系70个)APS(氯丙嗪或利培酮)单药治疗10周,治疗前后测量体重并计算体重指数。采用聚合酶链反应-限制性片段长度多态技术分析5-HTR2A基因启动区-1438G/A多态性基因型和等位基因分布频率,进行APS所致体重增加与5-HTR2A基因启动区-1438G/A多态性的相关分析、传递不平衡检验及数量性状传递不平衡检验。结果治疗10周后患者体重较基础体重增加(8.00±6.13)%。APS治疗10周后,体重增加≥7%和<7%患者组间,5-HTR2A基因-1438G/A多态性各基因型和等位基因分布频率差异均无统计学意义(P>0.05)。5-HTR2A基因-1438G/A多态性的各基因型之间各项指标的差异均无统计学意义(P>0.05);同时未发现5-HTR2A基因-1438G/A在不同体重增加组间存在传递不平衡。结论5-HTR2A基因-1438G/A多态性可能不是影响APS所致体重增加的主要遗传因素。     

A 5-HT2C receptor promoter polymorphism (HTR2C - 759C/T) is associated with obesity in women, and with resistance to weight loss in heterozygotes.

The serotonin 5-HT(2C) receptor (HTR2C) helps regulate appetite and body weight. An HTR2C promoter polymorphism (-759C/T) has been associated with obesity and with weight gain in response to antipsychotic (neuroleptic) drugs. We studied this polymorphism in 120 obese women (BMI > or = 30) and 104 non-obese (BMI < or = 25) women. The C allele was commoner in the obese group (OR = 1.72 [95% CI, 1.13-2.64], P = 0.008). Ninety-five of the obese women participated in a randomized trial of psychological treatments for weight loss. Among these women, heterozygotes lost less weight during the trial than did homozygotes (6.8 vs. 9.7 kg; P = 0.047) and weighed more 6 months (90.1 vs. 83.6 kg; P = 0.006) and 12 months (91.8 vs. 84.6 kg; P = 0.009) later. Heterozygotes also had higher triglyceride levels than homozygotes. C/C subjects in the obesity trial did not differ from T/T subjects in terms of weight loss or triglycerides. In a separate RT-PCR study of 43 subjects, we found that HTR2C mRNA abundance in frontal cortex was unaffected by -759C/T status. Our data extend the evidence that HTR2C promoter variation may be a risk factor for obesity and, perhaps through heterosis, influences weight loss by obese women. Pharmacogenetic testing of HTR2C promoter variants may be valuable when evaluating anti-obesity drugs which act directly or indirectly on the receptor.     

Association analysis of 5-HTTLPR variants, 5-HT2a receptor gene 102T/C polymorphism and migraine

It is well known that migraine has a strong genetic component, although the type and number of genes involved is not yet clear. There is evidence to suggest that serotonin-related genes participate in the pathogenesis of migraine. Previous studies have shown that gender differences influence the serotonergic neurotransmission and, in addition, the migraine prevalence is higher in females than males. Therefore, we investigated the functional polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) and the 102T/C polymorphism of the 5-HT2A receptor gene in the Hungarian female population. These genes were analysed in 126 migraine sufferers (with or without aura)and 101 unrelated healthy controls using case control design. A borderline association (chi2 = 3.84, df = 1, p = 0.049; OR = 1.45, 95% CI = 1.00-2.12) between 5-HTTLPR short (S) allele and migraine was found. No significant difference between migraine sufferers and controls was observed for the 102T/C polymorphism of 5-HT2A receptor gene. Furthermore, there was no significant interaction between5-HTTLPR and 102T/C polymorphisms in our study population. In conclusion, our results support that the genetic susceptibility of migraine may be associated with a locus at or near the 5-HT transporter gene.     

No association or linkage between the 5-HT2a/T102C polymorphism and schizophrenia in Irish families

Recent findings of an association between schizophrenia and a T102C polymorphism at the 5-HT^2a receptor gene (particularly with genotype 1-2 and 2-2 and allele 2) prompted us to investigate this marker in familial Irish schizophrenic patients, their relatives, and ethnically matched unrelated controls; 247 probands and 249 controls were included in this study. In contrast to some studies, we found no evidence of significant differences either in the frequency of the genotypes 1-2 and 2-2 or allele 2 between the schizophrenic patients and the controls. A transmission disequilibrium test, run on the full set of 265 families yielded no evidence to support linkage disequilibrium. Linkage analysis with both parametric and non-parametric methods yielded strongly negative results. Our findings are consistent with other recent association studies which argue against the involvement of the 5-HT_2a/T102C polymorphism in predisposition to schizophrenia. The positive findings reported to date might have occurred by chance or the apparent conflict may be due to genetic heterogeneity between samples. Am. J. Med. Genet. 74:370–373, 1997. © 1997 Wiley-Liss, Inc.     

Lack of an association between 5-HT1A receptor gene structural polymorphisms and suicide victims

A serotonergic dysfunction in the brain has been reported to be involved in suicidal behavior independently of the presence of a specific psychiatric disorder. Serotonin 1A (5-HT1A) receptors are known to be located on serotonergic nerve terminals and to be involved in the presynaptic regulation of serotonin release. Genetic factors partly explain the risks for suicide, and a suicide completion group is thought to be more uniform than a suicide attempt group. To explore the hypothesis that the 5-HT1A receptor-induced serotonergic dysfunction is implicated genetically in suicide, we focused on the structural polymorphisms, Pro16Leu and Gly272Asp, of the 5-HT1A receptor gene, and examined the association between suicide victims who completed suicide and these two polymorphisms. In both polymorphisms, we found no significant difference in genotype distribution or allele frequencies between suicide victims and controls. These findings suggest that neither of these two polymorphisms is associated with suicide victims and it is unlikely that the 5-HT1A receptor gene is implicated in the susceptibility to suicide.     

Lack of association of serotonin-2A receptor gene polymorphism (T102C) with suicidal ideation and suicide

Serotonergic dysfunction has been implicated in the pathophysiology of affective disorders and suicidality. Especially the density of the 5-HT2A receptor was claimed as being increased in suicidality, proposed as an adaptive upregulation due to reduced serotonergic transmission. Recent studies have shown an association of allele C of the 5-HT2A-T102C polymorphism with suicidal ideation in patients with major depression. The purpose of this study was to test whether this proposed marker indicates susceptibility not only to suicidal ideation in depressed patients but also to suicidality as a syndrome. We investigated the 5-HT2A-T102C polymorphism in 131 suicide victims with unknown underlying psychiatric diagnoses, 84 patients with major depression with or without suicidal ideation, and 125 healthy controls. We were unable to find any association of genotype or allele frequencies to major depression, suicidal ideation, or suicide as a syndrome. Thus, our results suggest that this polymorphism may not commonly be involved in the susceptibility to suicidality. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:831-835, 2000.     

Lack of association of serotonin‐2A receptor gene polymorphism (T102C) with suicidal ideation and suicide

Serotonergic dysfunction has been implicated in the pathophysiology of affective disorders and suicidality. Especially the density of the 5‐HT2A receptor was claimed as being increased in suicidality, proposed as an adaptive upregulation due to reduced serotonergic transmission. Recent studies have shown an association of allele C of the 5‐HT2A‐T102C polymorphism with suicidal ideation in patients with major depression. The purpose of this study was to test whether this proposed marker indicates susceptibility not only to suicidal ideation in depressed patients but also to suicidality as a syndrome. We investigated the 5‐HT2A‐T102C polymorphism in 131 suicide victims with unknown underlying psychiatric diagnoses, 84 patients with major depression with or without suicidal ideation, and 125 healthy controls. We were unable to find any association of genotype or allele frequencies to major depression, suicidal ideation, or suicide as a syndrome. Thus, our results suggest that this polymorphism may not commonly be involved in the susceptibility to suicidality. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:831–835, 2000. © 2000 Wiley‐Liss, Inc.     

The 5-HT(2A) receptor gene 102T/C polymorphism is associated with suicidal behavior in depressed patients.

Several lines of evidence suggest that genetic factors constitute an important determinant of suicidal behavior. A significant association between the 5-HT(2A)-C allele and suicidality has recently been reported. The aim of this study was to investigate whether the proposed association between 5-HT(2A)-102T/C polymorphism and suicidality could be replicated in a larger and independent sample of Spanish patients with major depression. The 102T/C polymorphism of the 5-HT(2A) receptor gene was analyzed in 159 patients with major depression (DSM-IV criteria) and 164 unrelated and healthy controls using a case control design. All individuals were subjects of Spanish origin. Significant differences in allele (chi-square = 4.13, df = 1, P = 0.04) and genotype (chi-square = 6.19, df = 2, P = 0.04) distributions were found between non-suicide attempters and suicide attempters. Moreover, those patients carrying 5-HT(2A)-C allele had more than five times the risk for attempting suicide than noncarriers (OR = 5.50, 95% CI = 1.18-35.20, P = 0.01). Our results replicate the proposed association between 5HT(2A)-C allele and suicidality in major depression. Moreover, no overall associations are detected when patients with major depression and controls are compared for 102T/C frequencies, suggesting that the increased risk for suicidality conferred by 5-HT(2A)-C allele is primarily associated with suicidal behavior and not with the diagnosis of major depression itself.     

Lack of association between variations in the melanocortin 5 receptor gene and bipolar disorder

OBJECTIVE: The melanocortin 5 receptor gene maps to the bipolar susceptibility locus on chromosome 18p11.2. Given the biological role of melanocortins and their influence on the hypothalamic-pituitary-adrenal axis, the melanocortin 5 receptor gene is a plausible candidate gene for bipolar disorder. We tested the hypothesis that the potential functional variation Phe209Leu confers susceptibility to bipolar disorder in a case-control study. METHODS: Genotypes for two variations in the coding region and one variation approximately 7 kb upstream from the coding region were obtained from 345 unrelated bipolar I patients and 275 control samples. Genotypes and allele frequencies were compared between groups using chi(2) contingency analysis. RESULTS: Allele frequencies of the Phe209Leu polymorphism did not differ significantly between bipolar patients and controls (P=0.679). Allele frequencies of the C744T and the intergenic A/G polymorphism did not differ significantly between bipolar patients and controls. All variations were in strong linkage disequilibrium. CONCLUSION: Variations in the melanocortin 5 receptor gene are unlikely to confer susceptibility to bipolar disorder in this sample. Further studies are required to elucidate the susceptibility locus for bipolar disorder on chromosome 18p11.     

Association analysis of the 5-HT6 receptor polymorphism C267T in Alzheimer's disease

Serotonergic dysfunction has been implicated in the pathogenesis of Alzheimer's disease (AD). This association study explores whether the serotonin 6 receptor (5-HT6) polymorphism (C267T) is a susceptibility factor for AD. Statistical analysis showed a significant difference in the genotype and gene frequencies between the AD group and the normal controls (P = 0.006; and P = 0.023, respectively). These findings indicate that the 267C allele of the 5-HT6 gene is a risk factor for AD.     

Lack of association between body weight, bone mineral density and vitamin D receptor gene polymorphism in normal and osteoporotic women

In an ethnically homogeneous population of women living in Tuscany, Italy, the relationships between age, body weight, bone mineral density and the vitamin D receptor (VDR) gene polymorphism were studied, with the objective of recognizing patients at risk for osteoporosis. In 275 women bone mineral density was measured by Dual Energy X-rays Absorptiometry (DEXA). In 50 of them the individual genetic pattern for VDR was evaluated by DNA extraction followed by PCR amplification of the VDR gene, and digestion with the restriction enzyme BsmI. Age and bone mineral density were inversely related (R2 = 0.298). Body weight was associated with bone mineral density (R2 = 0.059), but not with age. In osteoporotic women, mean (+/- SD) body weight was 59.9 +/- 6.5 Kg, lower than that recorded in non osteoporotic women (64.2 +/- 9.4 Kg), even though not significantly different (p = 0.18). No association was found between VDR gene polymorphism, bone density or body weight. The performance of anthropometric and genetic components appear to be poor, and, at least for the time being, bone mineral density measurement by means of MOC-DEXA represents the optimal method to detect women at risk for postmenopausal osteoporosis.     

Association between the C957T polymorphism of the dopamine D2 receptor gene and schizophrenia

The aim of this study was to investigate the relationship between the functional C957T single-nucleotide polymorphism of the dopamine D2 receptor (DRD2) gene and the risk for schizophrenia. We therefore conducted a case-control association study of 188 Finnish schizophrenia patients meeting the DSM-IV criteria and 384 healthy controls. The 5' nuclease assay (TaqMan) was used to determine genotypes. A greater proportion of patients with schizophrenia than healthy controls were C-allele carriers (odds ratio 1.5, 95% confidence interval (CI) 1.0-2.3, P=0.05). Our results are in agreement with an earlier association study suggesting that the C957T C-allele plays a role in the genetic vulnerability for schizophrenia and support the involvement of the DRD2 gene in schizophrenia pathogenesis.     

Lack of association between the corticotrophin-releasing hormone receptor 2 gene and panic disorder

Panic disorder is classified as an anxiety disorder and affects 1-3% of the population. An individual suffering from such a disorder may experience unexpected recurrent panic attacks and fear of future attacks. Twin and family studies have pointed towards a strong heritability of the disorder. Stress response and anxiety are thought to be mediated, at least in part, by the corticotrophin-releasing hormone (CRH), which is known to be a regulator of the hypothalamic-pituitary-adrenal pathway. To search for markers conferring genetic susceptibility to panic disorder, we typed three polymorphisms of the CRHR2 gene - CRHR2(CA), CRHR2(GT), and CRHR2(GAT) - in 466 individuals, 183 of whom had DSM-IV panic disorder. Seventy-five case-controls and 101 triad families plus 13 siblings were examined. Case-control association analyses using chi(2) tests yielded no difference in the distribution of the alleles. Linkage analysis using the Transmission Disequilibrium Test showed no preferential transmission of alleles for any of the three markers. Haplotype analysis indicated that allele 7 of CRHR2 (GAT) and 8 of CRHR2 (GT) are in almost complete linkage disequilibrium (P = 0.000 000 1). Although both neurobiology and chromosomal location point to the CHRH2 receptor gene as a candidate for panic disorder, our study indicates that the CRHR2 polymorphisms examined do not confer susceptibility to panic disorder. Further studies investigating additional polymorphisms in this gene and other components of the CRH signalling system may prove useful.