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‐HT_1A) 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‐HT_1A receptor‐induced serotonergic dysfunction is implicated genetically in suicide, we focused on the structural polymorphisms, Pro16Leu and Gly272Asp, of the 5‐HT_1A 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‐HT_1A receptor gene is implicated in the susceptibility to suicide. © 2002 Wiley‐Liss, Inc.     

Lack of association between interleukin-1 alpha,beta polymorphisms and Parkinson's disease

The associations between interleukin-1 alpha (IL-1α-889) and beta (IL-1β-511) single nucleotide polymorphisms (SNPs) and the risk for Parkinson's disease (PD) are still controversial and ambiguous. The aim of this study was to determine a more precise estimation of the relationship by meta-analysis. We searched databases through March 2010 for all publications on the association between these variations and PD. A total of 11 studies including 2803 PD patients and 2539 healthy controls were identified. The overall and geographic subgroups analysis was conducted, and odds ratios (OR) and 95% confidence intervals (95% CI) were calculated in the fixed- or random-effects model. We found that the overall OR (95% CI) for TT and CT genotypes versus CC genotype for IL-1α-889 was 1.01 (0.88–1.16), while the overall OR (95% CI) for TT and CT genotypes versus CC genotype for IL-1β-511 was 1.19 (0.87–1.62). The sensitivity analysis strengthened our confidence in the validity of these null associations. There was no publication bias observed in this study. To sum up, there were no associations found between the SNPs of IL-1α-889, IL-1β-511 and risk for PD.     

G‐protein coupled receptors and ligands that organize humoral immune responses

B‐cell responses are dynamic processes that depend on multiple types of interactions. Rare antigen‐specific B cells must encounter antigen and specialized systems are needed—unique to each lymphoid tissue type—to ensure this happens efficiently. Lymphoid tissue barrier cells act to ensure that pathogens, while being permitted entry for B‐cell recognition, are blocked from replication or dissemination. T follicular helper (Tfh) cells often need to be primed by dendritic cells before supporting B‐cell responses. For most responses, antigen‐specific helper T cells and B cells need to interact, first to initiate clonal expansion and the plasmablast response, and later to support the germinal center (GC) response. Newly formed plasma cells need to travel to supportive niches. GC B cells must become confined to the follicle center, organize into dark and light zones, and interact with Tfh cells. Memory B cells need to be positioned for rapid responses following reinfection. Each of these events requires the actions of multiple G‐protein coupled receptors (GPCRs) and their ligands, including chemokines and lipid mediators. This review will focus on the guidance cue code underlying B‐cell immunity, with an emphasis on findings from our laboratory and on newer advances in related areas. We will discuss our recent identification of geranylgeranyl‐glutathione as a ligand for P2RY8. Our goal is to provide the reader with a focused knowledge about the GPCRs guiding B‐cell responses and how they might be therapeutic targets, while also providing examples of how multiple types of GPCRs can cooperate or act iteratively to control cell behavior.     

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.     

DJ‐1 is a Parkinson's disease susceptibility gene in southern Italy

De Marco EV, Annesi G, Tarantino P, Nicoletti G, Civitelli D, Messina D, Annesi F, Arabia G, Salsone M, Condino F, Novellino F, Provenzano G, Rocca FE, Colica C, Morelli M, Scornaienchi V, Greco V, Giofrè L, Quattrone A. DJ‐1 is a Parkinson's disease susceptibility gene in southern Italy. Mutations in the gene DJ‐1 have been shown to be a rare cause of early‐onset Parkinson's disease (EOPD). Since DJ‐1 mutations have been found in patients with Parkinson's disease (PD) from southern Italy, we aimed to investigate whether polymorphisms within the DJ‐1 gene could represent a risk factor for sporadic PD. First, we genotyped 294 patients with PD and 298 controls coming from southern Italy to assess the distribution of the insertion/deletion (Ins/Del) polymorphism. In a second phase, we identified five single‐nucleotide polymorphisms (SNPs) useful to delimit a region potentially involved and genotyped all patients and controls for these markers. All the markers analyzed were significantly associated with PD at both allelic and genotypic level. The most significant association with the disease was found at the Ins/Del polymorphism (p = 0.0001; adjusted odds ratio (OR ) = 2.05; confidence interval (CI ) = 1.36–3.08). When we considered a three‐marker sliding window, we found a highly significant association between the disease and the haplotypes including markers rs17523802, Ins/Del, and rs3766606 (p = 0.0007) and markers Ins/Del, rs3766606 and rs7517357 (p = 0.0054). Our results indicate that polymorphisms located in a region spanning 3535 bp from the promoter to the intron 2 of the DJ‐1 gene confer risk to sporadic PD in southern Italy.     

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. © 2000 Wiley‐Liss, Inc.     

Lack of association of human chemokine receptor gene polymorphisms CCR2‐64I and CCR5‐Δ32 with autoimmune Addison's disease

The attraction of leukocytes to tissues is essential for inflammation and the initiation of the autoimmune reaction. The process is controlled by chemokines, which are chemotactic cytokines. We investigated whether human chemokine receptor gene polymorphisms, namely CCR5‐Δ32 and CCR2‐64I, are associated with susceptibility to autoimmune Addison's disease. Genotyping was performed in 56 patients and 127 healthy controls by a new method using pyrosequencing for CCR2‐64I and by polymerase chain reaction and detecting gel for CCR5‐Δ32. None of the CCR2 or CCR5 alleles was found to be associated, either positively or negatively, with disease risk. Our results indicate that the CCR2‐64I and CCR5‐Δ32 gene polymorphisms do not play a major role in conferring genetic risk for, and/or protection against, autoimmune Addison's disease.     

Overexpression of leucine‐rich repeat‐containing G protein‐coupled receptor 5 in gastric cancer

Gastric cancer is one of the most common malignancies worldwide and patients with advanced gastric cancer still have poor clinical outcomes. The overexpression of leucine‐rich repeat‐containing G protein‐coupled receptor 5 (LGR5) mRNA in colorectal cancer and its correlation with clinicopathological factors were recently reported by us. In this study, we show LGR5 mRNA overexpression in human gastric cancer specimens by quantitative RT‐PCR and in situ hybridization and assess a correlation with clinicopathological factors. The mean expression of LGR5 mRNA in cancerous tissues was five times higher than that in normal tissue (P = 0.0002). Furthermore, LGR5 mRNA expression show marked variation among cases and significantly increased in cases where lymphatic invasion was present compared with those where it was absent (P = 0.0056). Although the mean expression level of LGR5 was observed to be higher in nodal metastasis and venous invasion positive cases compared to negative cases, a significant difference was not observed. These results suggest that LGR5 can be a biomarker for malignancy in gastric cancer.     

Single nucleotide polymorphisms and haplotype frequencies of CYP3A5 in a Japanese population

In order to identify single nucleotide polymorphisms (SNPs) and haplotype frequencies of CYP3A5 in a Japanese population, we sequenced the proximal promoter region, all exons, and the surrounding intronic regions using genomic DNA from 187 Japanese subjects. Thirteen SNPs, including seven novel ones: 13108T>C, 16025A>G, 16903A>G, 16993C>G, 27448C>A, 29782A>G, and 31551T>C (A of the translational start codon of GenBank Accession # NG_000004.2 is numbered 1 according to the CYP Allele Nomenclature), were identified. The most common SNP was 6986A>G (key SNP for CYP3A5*3), with a 0.759 frequency. Two novel SNPs, 29782A>G (I456V) and 31551T>C (I488T), as well as 12952T>C (*5 marker) were found, but these alterations were always associated with the *3A marker SNPs, 6986A>G and 31611C>T. Using these 13 SNPs, haplotype analysis was performed and five novel *1 haplotypes (subtypes) (*1e to *1i) and six novel *3 haplotypes (subtypes) (*3d to *3i) were identified. Our findings suggest that CYP3A5*3 is the major defective allele and that other functional exonic SNPs are rare in the Japanese.     

Seven novel sequence variants in the human low density lipoprotein receptor related protein 5 (LRP5) gene

We identified seven novel polymorphisms in the human low density lipoprotein receptor related protein 5 (LRP5) gene. Two of them are predicted to replace amino acid in LRP5 protein (c.314A>G: Q89R and c.4037T>C: V1330A), whereas three are silent mutations in the coding region (c.2268T>C: N740N, c.3405A>G: V1119V, and c.4137C>T: D1363D) and two are polymorphisms in introns (IVS10+6T>C and IVS17‐30G>A). Since LRP5 recognizes apolipoprotein E and is genetically linked with type 1 diabetes, these novel polymorphisms will be useful in genetic studies of hyperlipoproteinemia and diabetes. To our knowledge, this is the first report in the literature of sequence variants in the human LRP5 gene. ©2002 Wiley‐Liss, Inc.     

Genetic Polymorphisms and Haplotypes of the Human Cardiac Sodium Channel α Subunit Gene (SCN5A) in Japanese and their Association with Arrhythmia

Genetic variations in cardiac ion channels have been implicated not only as the causes of inherited arrhythmic syndromes, but also as genetic risk factors for some acquired arrhythmias. To elucidate the potential roles of genetic polymorphisms of the α subunit of the voltage‐gated sodium channel type V (SCN5A) in cardiac rhythm disturbance, the entire SCN5A coding exons and their flanking introns were sequenced in 166 Japanese arrhythmic patients and 232 healthy controls. We detected 69 genetic variations, including 54 novel ones. Out of the 12 novel nonsynonymous single nucleotide polymorphisms (SNPs), p.Leu1988Arg was found at a frequency of 0.015. The other 11 SNPs were rare (0.001), with 6 found in arrhythmic patients and 5 in healthy controls. The frequency of a novel intronic SNP, c.703+130G>A, was significantly higher in the patients than in the controls, suggesting this SNP is associated with an unknown risk factor for arrhythmia. Following linkage disequilibrium analysis, the haplotype structure of SCN5A was inferred using high‐frequency SNPs. The frequency of the haplotype harbouring both p.Leu1988Arg and the common SNP p.His558Arg (haplotype GG) was significantly lower in the patients than in the controls. This finding suggests that this haplotype (GG) might have been positively selected in the controls because of its protective effect against arrhythmias. This study provides fundamental information necessary to elucidate the effect of genetic variations in SCN5A on channel function and cardiac rhythm in Japanese, and probably in the Asian population.     

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.     

Association between polymorphisms in catechol‐O‐methyltransferase (COMT) and cocaine‐induced paranoia in European‐American and African‐American populations

Catechol‐O‐methyltransferase (genetic locus, COMT) is a major enzyme involved in catecholamine metabolism and has been associated with numerous psychiatric phenotypes. We studied COMT SNPs and haplotypes in cocaine‐induced paranoia (CIP) in African‐American (AA) and European‐American (EA) populations. We genotyped 17 SNPs across the COMT locus in 319 AA pedigrees (848 individuals) and 302 EA pedigrees (707 individuals). Family‐controlled association analyses were conducted using FBAT. We found SNP rs737865 to be nominally significantly associated in the AA family population (P = 0.05). In EAs, the best‐known marker, rs4680 (Val158Met), was nominally significant in additive models (P = 0.03). SNP rs174696 also showed nominal significance in additive models (P = 0.02). We considered the three SNPs (rs737866–rs4680–rs174696) together in haplotype analysis in both family populations, using HBAT. The A–A–T haplotype was significantly associated with CIP in EAs (Z = 2.845; P = 0.0044, global P = 0.020). We then studied COMT SNPs in an additional 738 AA and 404 EA unrelated cocaine dependent individuals with and without paranoia. The A–A–T haplotype was significantly associated to CIP in the AA unrelated population (P = 0.0015). Two haplotypes, A–G–C and A–A–C, were significant in the EA unrelated population (P = 0.001 and 0.0003). We also identified rs4680 and three other SNPs, rs933271, rs5993883, and rs740603, as potentially functional variants, as predicted by a signature of positive selection in unrelated EAs and AAs. Based on our robust family‐controlled and unrelated‐affected analyses, we conclude that COMT is associated with CIP, possibly as a result of its role in the metabolism of dopamine and norepinephrine. © 2011 Wiley‐Liss, Inc.