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Biomedical subjects

M Emin Erdal

Publications and source records attributed to M Emin Erdal.

14 recordsLinked to original sources
PubMed2006

DRD4 and DAT1 polymorphisms modulate human gamma band responses.

Gamma oscillations (30-80 Hz) have been demonstrated to be important for perceptual and cognitive processes. Animal and in vitro studies have revealed possible underlying generation mechanisms of the gamma rhythm. However, little is known about the neurochemical modulation of these oscillations during human cognition. Schizophrenia and Attention Deficit Hyperactivity Disorder, which lead to failure of attentional modulation and working memory, introduce significant changes in gamma responses and have significant associations with genetic polymorphisms of dopamine receptor D4 (DRD4), dopamine transporter (DAT), and catechol-O-methyltransferase (COMT). Therefore, the presence of direct relations between these polymorphisms and gamma oscillations was investigated in human subjects using an auditory target detection paradigm. The 7-repeat isoform of the DRD4 polymorphism that produces a subsensitive variant of the D4 receptor enhanced the auditory evoked and induced gamma responses to both standard and target stimuli. The 10/10 genotype of the DAT1 polymorphism, which reduces DAT expression and hence yields an increase in extracellular dopamine, specifically enhanced evoked gamma responses to target stimuli. The COMT polymorphism did not significantly change gamma responses. It seems plausible to assume that the modulation pattern of the evoked gamma response by DRD4 polymorphism relates to reduced inhibition via the D4 receptor, whereas the DAT1 effect is related to the target detection mechanism probably mediated by the D1 receptor.

Adaptation, Physiological↗
PubMed2006

Lack of association with TNF-alpha-308 promoter polymorphism in patients with vitiligo.

Vitiligo is an acquired depigmentary disorder of the skin, characterized by incomplete penetrance, multiple susceptibility loci and genetic heterogeneity. An immunologic hypothesis is currently advanced as a possible pathogenesis of vitiligo. The cytokines have an important role in pathogenesis of autoimmunity in which tumor necrosis factor-alpha (TNF-alpha), a paracrine inhibitor of melanocytes, is especially important. Several single-nucleotide polymorphisms (SNP) have been identified in the human TNF gene promoter. The polymorphism at position -308 (TNF-308), which involves substituting G for A and designing the AA genotype, leads to a higher rate of TNF gene transcription than the wild-type GG genotype in in vitro expression studies. It has also been linked to increased susceptibility to several chronic metabolic, degenerative, inflammatory and autoimmune diseases. Therefore, we investigated the TNF-alpha-308 SNP in patients with vitiligo. We examined 61 patients with vitiligo. Healthy age-, ethnically- and sex-matched individuals (n = 123) served as controls. Polymerase chain reaction amplification was used for analysis of the polymorphism at position -308 in promoter of TNF-alpha gene. We found that the distribution of TNF-alpha genotypes in vitiligo patients did not differ from that in control subjects (P > 0.05). Moreover, there was no association between TNF-alpha genotypes and types of vitiligo. In conclusion, we suggest that TNF-alpha-308 SNP is not a genetic risk factor for vitiligo susceptibility.

Case-Control Studies↗
PubMed2005

Association of serotonin transporter gene polymorphism with obstructive sleep apnea syndrome.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) is a common condition characterized by repetitive pharyngeal collapse during sleep and daytime sleepiness. There is genetic predisposition to sleep disorders. Serotonin is involved in the regulation of sleep. The synaptic 5-hydroxytryptamine (HT) is inactivated by presynaptic reuptake, which is mediated by the serotonin transporter. Blockage of the serotonin transporter leads to increased extracellular 5-HT. Polymorphism of the serotonin transporter gene (STG) leads to alterations in serotonin level and may be important in OSAS. In this study, we aimed to assess the role of STG polymorphism in OSAS. METHODS: Twenty-seven OSAS patients and 162 healthy volunteers were involved in the study. STG polymorphism was investigated using leukocytes obtained from peripheral blood. RESULTS: There was no difference between the genotypes and allele frequencies of the patients and controls regarding VNTR and HTTLPR polymorphisms (P > .05). The VNTR and HTTLPR variants and the frequencies of 12/12, 12/10, L, and S alleles were not significantly different between male and female control subjects (P > .05). The 12/12 and SS genotypes were over-represented in the female patients, whereas 12/10 and LL genotypes were over-represented in the male patients (P < .05). The genotypes 12 to 12 were over-represented in the male controls, whereas the genotypes 12 to 10 and L/S were over-represented in the male patients (P < .05). The alleles 10 and L were more frequent in the male patients than male controls (P < .05). The genotypes of female patients and female controls were not significantly different (P > .05). The allele 10 and L were less frequent in the female patients than female controls with Fisher's exact testing (P < .05). There was no relation between genotypes and clinical data of the patients (P > .05). CONCLUSION: STG polymorphism appears to be associated with the occurrence of OSAS, especially in male patients. Absence of association of between genetic variants and polysomnography findings may suggest that some mechanisms other than STG polymorphism are involved in OSAS pathophysiology. Our results need confirmation in a larger group of patients with OSAS.

DNA Primers↗
PubMed2003

Lack of association of catechol-O-methyltransferase gene polymorphism in obsessive-compulsive disorder.

The COMT gene has been implicated to be involved in the pathogenesis of obsessive-compulsive disorder (OCD) and various other psychiatric disorders. COMT enzyme activity is governed by a common genetic polymorphism at codon 158 that results in substantial 3- to 4-fold variation in enzymatic activity [a high-activity COMT variant (H) and a low activity variant (L)]. This study evaluates the association between OCD and the COMT gene polymorphism. Fifty-nine OCD patients that were diagnosed according to DSM-IV criteria and 114 healthy control subjects were included in the study. PCR technique was used for molecular analysis. The genotypic pattern of distribution of the COMT gene (H/H, H/L, and L/L genotypes) was not different between the OCD patients and controls. There were no significant differences among the patients with positive family history for OCD, those with negative family history for OCD, and the controls with respect to allele frequencies of the COMT gene polymorphisms. Patients that were homozygous or heterozygous for the L allele had significantly higher insight scores (i.e., poorer insight) on Y-BOCS compared to those homozygous for the H allele. We did not find an association between OCD, family history for OCD, and the COMT gene polymorphism. This study suggests that the COMT gene polymorphism is not directly associated with OCD in our patient group.

Adolescent↗
PubMed2003

Tardive dyskinesia is not associated with the polymorphisms of 5-HT2A receptor gene, serotonin transporter gene and catechol-o-methyltransferase gene.

BACKGROUND: The pathophysiology of tardive dyskinesia (TD) is not completely understood.Aim. - To assess the relationship of TD with 5-HT2A receptor gene, serotonin transporter gene (5 HTT), and catechol-o-methyltransferase (COMT) gene polymorphisms. METHOD: Our study comprised 111 unrelated subjects who strictly met DSM-IV criteria for schizophrenia and 32 TD, and 79 healthy unrelated controls; all the subjects were of Turkish origin. The analyses of 5-HT2A receptor gene, 5 HTT gene, and COMT gene polymorphisms were performed using polymerase chain reaction (PCR) technique. RESULTS: The polymorphisms of these genes were not significantly different between the schizophrenic patients, TD and control subjects. CONCLUSION: Our findings indicated that 5-HT2A receptor gene, 5 HTT gene, and COMT gene polymorphisms were similar in schizophrenia with non-TD, schizophrenia with TD, and healthy controls. These polymorphisms, though, do not help to evaluate the susceptibility to TD.

Adult↗
PubMed2003

T102C and -1438 G/A polymorphisms of the 5-HT2A receptor gene in Turkish patients with obsessive-compulsive disorder.

OBJECTIVE: This study aimed to investigate the possible association between T102C and -1438 G/A polymorphism in the 5-HT2A receptor gene and susceptibility to and clinical features of obsessive-compulsive disorder (OCD). METHOD: Fifty-eight patients with OCD and 83 healthy controls were included in the study. All patients were interviewed and rated by Yale-Brown Obsessive-Compulsive Scale. T102C and -1438 G/A polymorphisms of 5-HT2A receptor gene were determined by PCR technique in DNAs of peripheral leucocytes. RESULTS: OCD patients and healthy controls did not show significant differences in genotype distribution for both polymorphisms investigated. We found that frequencies of the TT genotype for T102C polymorphism and the AA genotype for -1438 G/A polymorphism were significantly higher in patients with severe OCD compared to those with moderate or moderate-severe OCD. CONCLUSION: The -1438 G/A and T102C polymorphisms of the 5-HT2A receptor gene are not associated with an increased risk of OCD. Our data suggest that the TT genotype of T102C and the AA genotype of -1438 G/A polymorphism might be a factor in clinical severity of OCD.

Adolescent↗
PubMed2003

T102C polymorphisms at the 5-HT2A receptor gene in Turkish schizophrenia patients: a possible association with prognosis.

BACKGROUND: Serotonergic system abnormalities have been implicated in the pathogenesis of schizophrenia. The 5-HT2A receptor gene polymorphism has long been implicated to play a role in the pathogenesis of schizophrenia. AIM: In this study, we assessed the relationship of schizophrenia and its subgroups with 5-HT2A receptor gene polymorphism, and attempted to evaluate a possible correlation between the severity and prognosis of the illness and 5-HT2A receptor gene polymorphism. METHOD: Our study comprised 141 unrelated subjects who strictly met DSM-IV criteria for schizophrenia, and 79 healthy unrelated controls, all of Turkish origin. A clinical evaluation of all patients was accomplished applying the Brief Psychiatric Rating Scale (BPRS) test. The analysis of 5-HT2A receptor gene polymorphism was performed using the polymerase chain reaction technique. RESULTS: Regarding 5-HT2A receptor gene polymorphisms, no statistically significant difference was found between schizophrenic patients and control subjects (p > 0.05). There was no significant difference between the average of BPRS points of the patients and 5-HT2A receptor gene polymorphisms (p > 0.05). Although there was no correlation between the duration of illness and polymorphism (p > 0.05), the frequency of hospitalization was found to be higher in the patients with T/C and T/T genotypes compared with the patients with C/C genotype (p < 0.05). CONCLUSION: Our findings indicate that the T102C polymorphisms of the 5-HT2A receptor gene does not play a substantial role in schizophrenia nor help evaluate susceptibility to schizophrenia. Since the 5-HT2A receptor gene polymorphism is associated with the frequency of hospitalization of the patients, it may be an indicator of prognosis in schizophrenia or help differentiate the patients who are somewhat refractory to antipsychotic treatment.

Adult↗
PubMed2002

Association between the N-acetylation genetic polymorphism and bronchial asthma.

AIMS: Since polymorphic N-acetyltransferase 2 (NAT2) has been suggested as a susceptibility factor for atopic diseases, the study was undertaken to investigate whether an association exists between acetylation polymorphism and asthma patients with atopy. METHODS: The frequencies of NAT2 alleles and genotypes were determined by PCR/RFLP in a total of 210 asthma patients (extrinsic (n = 108) and intrinsic (n = 102) asthmatics) and 240 control subjects. Presence of the NAT2*4 (wild-type) allele defined a NAT2 genotype as rapid and combinations of mutant alleles NAT2*5 A, *5B, *5C, *6 A, and *7B as slow. RESULTS: Genotypes coding for slow acetylation were detected in 70.4, 58.4 and 58.3% of extrinsic asthmatics, but intrinsic asthmatics and control subjects, respectively. The frequency of slow acetylators was higher among extrinsic asthmatics than intrinsic asthmatics, this difference did not reach statistical significance (odds ratio 1.02, 95% confidence interval 0.64, 1.63, P = 0.085). However, we found a relatively moderate, but significantly higher, increased frequency of slow acetylators among extrinsic asthma patients compared with control subjects (odds ratio 1.70, 95% confidence interval 1.04, 2.76, P = 0.042). CONCLUSIONS: This study shows an association between acetylation polymorphism and susceptibility to extrinsic asthma, but not to intrinsic asthma, suggesting a minor role of the NAT2 polymorphism in the development of atopic asthma.

Acetylation↗
PubMed2002

Serotonin transporter gene polymorphism in irritable bowel syndrome.

OBJECTIVES: Serotonin is a key mediator of intestinal peristalsis, and after it is secreted, it is effectively cleansed from the neuronal gap by means of a high affinity substance called serotonin transporter (SERT), which depends on the Na+ and Cl- ions localized in the presynaptic neuronal membranes. The aim of this study was to investigate SERT polymorphism in patients with irritable bowel syndrome (IBS). METHODS: SERT gene polymorphism was assessed by polymerase chain reaction on DNA chains obtained from leukocytes in serum samples from 54 patients diagnosed with IBS and 91 healthy subjects. The polymorphism of two regions (variable number tandem repeats and the SERT gene-linked polymorphic region [5-HTTLPR]) of SERT was assessed. RESULTS: SERT polymorphisms were found to be similar in healthy subjects and IBS patients (p > 0.05). IBS patients were divided into three groups: diarrhea predominant (n = 18), constipation predominant (n = 26), and alternating diarrhea and constipation (n = 10). These groups were compared with respect to gene polymorphism, and it was found that the 5-HTTLPR allele S/S genotype occurred with greater frequency in the constipation predominant group than in the other two subgroups (p < 0.05), and L/S genotype frequency in the diarrhea predominant group was higher than those in the constipation and control groups. CONCLUSIONS: No relationship was found between IBS and SERT gene polymorphism. It is conceivable that the presence of the S/S genotype in IBS patients carries an increased risk of the constipation predominant type of IBS, whereas the presence of the 5-HTTLPR allele L/S genotype carries an increased risk of the diarrhea predominant type.

Adolescent↗
PubMed2001

Significance of the catechol-O-methyltransferase gene polymorphism in migraine.

The objective was to assess the significance of the catechol-o-methyltransferase (COMT) enzyme polymorphism in migraine. For this reason, 62 migraineurs and 64 healthy volunteers were included in the study. The analysis of COMT polymorphism was performed using PCR. The H/H genotype was more frequent in the control group than in the patients group (P=0.032). The homozygous or heterozygous L allele was over represented in the migraineurs compared with the controls (P=0.013). The L/L genotype was over represented in the migraineurs who also had a family history of migraine (P=0.003). There was no relationship between aura and COMT genotypes. In conclusion, the COMT polymorphism may be of potential pharmacological importance regarding the individual differences in the metabolism of catechol drugs in migraineurs. Although altered catecholamine activity due to polymorphism of COMT gene may be one of the mechanisms involved in the pathogenesis of migraine, these mechanisms are not related to presence or absence of aura.

Adult↗