Takehito Okubo

The (CTG)n polymorphism in the NOTCH4 gene is not associated with schizophrenia in Japanese individuals

BackgroundThe human NOTCH4 gene is a candidate gene for schizophrenia due to its chromosomal location and neurobiological roles. In a British linkage study, NOTCH4 gene polymorphisms were highly associated with schizophrenia. In a Japanese case-control association study, however, these polymorphisms did not show significant associations with schizophrenia. We conducted a case-control study with Japanese subjects to explore an association between the triplet repeat polymorphism in the NOTCH4 gene and schizophrenia, including subtypes of schizophrenia, longitudinal disease course characteristics, and a positive family history for psychoses.MethodsWe examined the (CTG)n repeat polymorphism in the NOTCH4 gene among 100 healthy Japanese individuals and 102 patients with schizophrenia (22 paranoid, 38 disorganized, 29 residual, 64 episodic, 31 continuous, 42 with prominent negative symptoms, and 46 with positive family histories) using a polymerase chain reaction-based, single-strand conformational polymorphism analysis.ResultsFive different alleles consisting of 6, 9, 10, 11, and 13 repeats of CTG (Leu) in patients with schizophrenia, and 4 alleles consisting of 6, 9, 10, and 11 repeats in controls were found. No significant differences in genotype or allele frequencies of repeat numbers were found between controls and patients. In addition, there were no associations between the polymorphism and schizophrenia subtypes, longitudinal disease course characteristics, or positive family history of the patients.ConclusionsOur data suggest a lack of association between the NOTCH4 gene triplet repeat polymorphism and schizophrenia in Japanese individuals.

Novel variants in the promoter region of the CREB gene in schizophrenic patients

AbstractCyclic AMP-responsive element-binding protein (CREB) is one of the messenger molecules involved in intracellular signal transduction pathways used by most dopamine and serotonin receptor subtypes. In addition, CREB stimulates the expression of a number of genes, alterations in the expression of which may be associated with schizophrenia. The promoter region of the human CREB gene was therefore analyzed to identify genetic variants that may lead to the modification of CREB expression and contribute to schizophrenia. Eighty unrelated schizophrenics and 100 healthy controls were screened for genetic variants of the CREB gene by SSCP analysis, followed by direct sequencing of PCR products. Two novel variants (−933T→C and −413G→A) were found only in schizophrenics. A patient with the −933T→C variant had unusual clinical characteristics in addition to typical schizophrenic symptoms.

A new genetic variant in the Sp1 binding cis-element of cholecystokinin gene promoter region and relationship to alcoholism

Neuropeptide cholecystokinin (CCK) and the CCK receptors in the central nervous system mediate actions on increasing firings, anxiety, and nociceptions. Furthermore, CCK modulates the release of dopamine and dopamine-related behaviors in the mesolimbic pathway. In our study, genetic variation in the promoter and coding regions of the prepro-CCK gene were analyzed among 66 Japanese, 66 American Whites, 54 Chinese, and 41 Colombian natives. Two nucleotide sequence variants were found: a frequent mutation at nucleotide position -45 C to T involved in core sequence of Sp1 binding cis-element of the promoter region, and a C to T substitution at the 1662 position in intron 2. Analysis for the segregation study in 10 families of twins confirmed codominant heredity of two alleles. Distribution of genotypes and gene frequencies of 66 controls and 108 alcoholics in Japan presented that allelic variant T type in alcoholics was found in higher frequencies than that of controls, and distribution of these genotypes was significantly different between the both groups.

Association analyses between polymorphisms of the phase II detoxification enzymes (GSTM1, NQO1, NQO2) and alcohol withdrawal symptoms.

BACKGROUND NRH-quinone oxidoreductase 2 (NQO2) along with glutathione S-transferase M1 (GSTM1) and NAD(P)H-quinone oxidoreductase 1 (NQO1), which is involved in phase II detoxification reactions, is thought to be important for detoxification of catechol o-quinones in the central nervous system. Our previous study revealed that the human NQO2 gene is highly polymorphic. In this study, we investigated a possible association between polymorphisms of the GSTM1, NQO1, and NQO2 genes and alcohol withdrawal symptoms such as delirium tremens, hallucination, and seizure. METHODS A total of 247 Japanese male alcoholic patients with alcohol withdrawal symptoms or without the symptoms, and 134 age-matched Japanese male controls (nonhabitual drinkers), were examined by using polymerase chain reaction (PCR), PCR restriction fragment length polymorphism, PCR-based single-strand conformational change polymorphism, and PCR direct sequencing analyses. RESULTS A significant difference was found between alcoholic patients and controls in genotype frequency at an insertion/deletion site in the promoter region of the NQO2 gene (p = 0.0014). The frequency of the homozygous genotype for the D allele at this locus was significantly higher in delirium tremens-positive patients (p = 0.0004) and in hallucination-positive patients (p = 0.0001), and in patients displaying both delirium tremens and hallucination (p = 0.0002), than in controls. The values were still significant after Bonferroni correction. On the other hand, no significant difference was detected for allele frequencies or genotype frequencies for the other polymorphic loci of the NQO2 gene. Moreover, GSTM1 gene deletion and missense mutation (Pro187Ser) of the NQO1 gene showed no significant association with alcohol withdrawal symptoms. CONCLUSION Present data suggest that an insertion/deletion polymorphism in the promoter region of the NQO2 gene plays an important role in the pathogenesis of alcoholism and alcohol withdrawal symptoms.

Polymorphism of the 5`-Upstream Region of the Human SNAP-25 Gene:An Association Analysis with Schizophrenia

Recent studies have suggested that synaptic abnormalities may be part of the pathophysiology of schizophrenia. SNAP-25 (synaptosomal-associated protein of 25 kD) is one of the synaptic proteins responsible for presynaptic neurotransmission, axonal elongation and synaptogenesis. Genetic variation in the 5′-upstream region of the SNAP-25 gene was analyzed in 87 unrelated schizophrenic patients and 100 healthy controls. A novel polymorphic (TAAA)n tandem repeat was identified in the 5′-upstream region. There were no significant differences between the patient and the control groups in the distribution of repeat numbers of alleles or genotypes. In addition, no associations were found between the polymorphism for subtypes, longitudinal courses or positive family history of the patients. Our results suggest that polymorphisms in the 5′-upstream region of the SNAP-25 gene have no association with schizophrenia.

Genetic Association Between Alcohol Withdrawal Symptoms and Polymorphism of CCK Gene Promoter

In the central nervous system, cholecystokinin (CCK) is an important neurotransmitter that gives the influences on firings, anxiety, notiception, and dopamine-related behavior. CCK co-exists in the dopaminergic neurons, interacting with dopamine. In this study, we examined the genetic variant -45 C to T substitution of the CCK gene promoter region among 195 healthy Japanese and 174 patients with alcohol withdrawal syndrome (52 delirium tremens, 39 hallucinosis, 20 seizures, and 92 lack of these symptoms) by using polymerase chain reaction-based single-strand conformational polymorphism analysis. Patients with delirium tremens showed a significantly higher frequency of the variant, compared with the controls (X2 = 4.91, p < 0.03), but patients with other symptoms showed no difference. These data suggested that the individuals possessing allelic mutation (-45T) in the promoter region of the CCK gene might be susceptible to delirium tremens caused by alcohol abuse.

Polymorphisms in the promoter and coding regions of the synapsin III gene. A lack of association with schizophrenia.

The human synapsin III gene, located on chromosome 22q12–13, has previously been reported to indicate a susceptibility for schizophrenia. Noval rare variants (Thr136Thr in exon 3, Pro468Ser, Glu525Gln and Pro534Leu in exon 12, and 1769 G/C in the untranslated region of exon 13) were found in addition to the polymorphic variant (–196 G/A in the promoter region). No significant differences in genotypic or allelic frequencies of the –196 G/A polymorphism were found between 87 unrelated schizophrenic patients and 100 healthy controls, even when the patients were diagnostically subdivided into subtypes and course specifiers. Furthermore, allelic frequencies of the GATG repeat in intron 1 were not significantly different between the patients and the controls. These results suggest that synapsin III gene polymorphisms are not associated with schizophrenia.

Novel polymorphisms of the AP-2 gene (6p24): analysis of association with schizophrenia.

AbstractThe transcription factor activator protein 2 (AP-2) gene is a possible candidate gene for schizophrenia, since it maps near D6S470, a marker on chromosome 6p24 that provided evidence of linkage to schizophrenia. In the present study we analyzed the promoter region and the whole coding region of the human AP-2 gene in order to identify genetic variations that may lead to the modification of AP-2 expression or the alteration of protein function, contributing to schizophrenia or particular schizophrenic phenotypes. Genomic DNA was isolated from the whole blood samples of 87 unrelated schizophrenics and 100 healthy controls. Polymerase chain reaction (PCR) was performed, using 15 primer sets that spanned the promoter region and the whole coding region, and amplified products were screened by single-strand conformational polymorphism (SSCP) analysis. Aberrant SSCP patterns were analyzed by direct sequencing. Three novel polymorphisms were found in the promoter region; two relatively common (−90G→C, −803G→T) and one rare (−1769G→A). Polymorphic status at both loci suggested strong linkage disequilibrium between the −90G and −803G alleles, and between the −90C and −803T alleles. Although no significant differences in genotypic and allelic frequencies at the −90 and −803 loci were found between patients and controls, significant differences in the distribution of genotypes at the −90 (P = 0.008) and −803 (P = 0.037) loci were observed in patients with an episodic course compared with controls. However, the difference for the −803 locus was not significant after Bonferroni correction for multiple comparisons. Our data provided no direct evidence of an association between schizophrenia and the polymorphisms of the AP-2 gene, although the positive result at the −90 locus in schizophrenics with an episodic course is potentially interesting.

Association analysis of polymorphisms in the prepronociceptin gene and schizophrenia

AbstractThe human prepronociceptin (ppNoc) gene is located on chromosome 8p21, and several linkage studies have suggested that the susceptibility locus for schizophrenia is present in this chromosomal region. We investigated genetic variations in the promoter and coding regions of the ppNoc gene to determine if there may be an association between naturally occurring mutations and the manifestation of schizophrenia. Association analyses for the variations found were conducted between 87 unrelated schizophrenic patients and 100 healthy controls. Polymorphisms were found at both the –503 locus (G/A) in the promoter region and the 353 locus (Ala118Gly) in exon 3. Additionally, rare variants were identified at the –261 locus (A/G) in the promoter region, the 515 locus (Gln172Arg) in exon 3, and the 561 locus (G/A) in the untranslated region of exon 3. A significant difference was observed in allele frequency at the 353 locus between controls and patients with continuous-course schizophrenia (P = 0.0237), and between patients with and without prominent negative symptoms (P = 0.0201). However, neither difference was significant after Bonferroni correction. In addition, there were no significant differences in genotype and allele frequencies at either the –503 or 353 locus between the control group and patients with schizophrenia. These results suggest that ppNoc gene polymorphisms have no association with schizophrenia.