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At least 181 records · Page 10Linked to original sources
PubMed2002

Schizophrenia and functional polymorphisms in the MAOA and COMT genes: no evidence for association or epistasis.

Several lines of evidence suggest that psychosis is associated with altered dopaminergic neurotransmission. Dopamine is catabolized by monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT). We hypothesized that the genes encoding MAOA and COMT might contain genetic variation conferring increased risk to schizophrenia. In order to test this hypothesis, we genotyped the 941T > G and the promoter VNTR polymorphisms in the MAOA gene and the V158M COMT polymorphism in 346 DSMIV schizophrenics and 334 controls. We also genotyped the-287A > G COMT promoter polymorphism in 177 schizophrenics and 173 controls. No significant differences were found in allele or genotype frequencies between affecteds and controls for any of the polymorphisms. As both genes are involved in degrading catecholamines, we also sought evidence for additive and epistatic effects but none was observed. Our data, therefore, do not support the hypothesis that genetic variation in MAOA and COMT is involved individually or in combination in the etiology of schizophrenia.

Adult↗
PubMed2003

Lack of association between serotonin 5-HT1B receptor gene polymorphism and suicidal behavior.

A genetic susceptibility to suicide attempts has been repeatedly suggested by family-, twin-, and adoption-studies. Because elevated impulsive aggression is one of the most prominent characteristics of suicide attempters and aggressive behavior has been reported in 5-HT1B receptor gene knockout mice, the serotonin receptor 1B gene (5-HT1B) is an attractive candidate. The distribution of a polymorphism (G861C) in the 5-HT1B gene was examined in 148 consecutively hospitalized German suicide attempters, and 327 German healthy volunteers randomly recruited from the general population. The controls and their first degree relatives had no history of mental disorders or suicidal behavior. We found no significant difference in allele or genotype frequency between patients and controls. The results did not differ when the patients were divided into several subgroups (gender, suicide attempters with a violent method or suicide attempters with unipolar-, bipolar-, borderline personality-, and schizophrenia spectrum disorders). These findings suggest that the 5-HT1B polymorphism is unlikely to play a major role in the genetic susceptibility to suicide attempts.

Adolescent↗
PubMed2006

Genotypic interaction between DRD4 and DAT1 loci is a high risk factor for attention-deficit/hyperactivity disorder in Chilean families.

Attention-deficit/hyperactivity disorder, ADHD [MIM 126452], is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness, and/or inattentiveness. As part of an ongoing study of ADHD, we carried out a family-based discordant sib-pair analysis to detect possible associations between dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms and ADHD in Chilean families. Both loci individually classified as homozygotes or heterozygotes for the DRD4 7-repeat and DAT1 10-repeat alleles, did not exhibit genotype frequency differences between affected children and their healthy siblings (Fisher's exact test P > 0.25 in both cases). However, the simultaneous presence of both DRD4 7-repeat heterozygosity and DAT1 10 allele homozygosity were significantly higher (34.6%) in cases (26), compared with their unaffected siblings (25) (4%; Fisher's exact test P = 0.0096; odds-ratio, OR = 12.71). Increased density of dopamine transporter in ADHD brains, along with abundance of 7-repeat D4 receptors in prefrontal cortex, which is impaired in ADHD patients, make the observed gene-gene interaction worthy of further incisive studies.

Adolescent↗
PubMed2005

Polymorphism in the nuclear excision repair gene ERCC2/XPD: association between an exon 6-exon 10 haplotype and susceptibility to cutaneous basal cell carcinoma.

Cutaneous basal cell carcinoma (BCC) risk is mediated by interactions between ultraviolet radiation (UVR) and host factors, including DNA repair efficiency. We investigated the association between BCC risk and SNPs in exon 6 (c.466C > A, dbSNP238406:g.C > A; designated C/A156), exon 10 (c.932G > A, dbSNP1799793:g.G > A; designated G/A312), and exon 23 (c.2251A > C, dbSNP13181:g.A > C; designated A/C751) of the nucleotide excision repair gene, XPD (ERCC2; excision repair cross-complementing repair deficiency, complementation 2 [xeroderma pigmentosum D]). XPD genotype frequencies were not significantly different in 509 cases and 379 controls, although AA156 (odds ratio [OR]=0.61, 95% confidence interval [CI]=0.37-1.01, P=0.052) and AA312 (OR=0.65, 95% CI=0.40-1.05, P=0.08) were linked with reduced risk. A156-A312 and A156-A312-A751 haplotype frequencies however, were significantly lower in cases than controls (OR=0.12, 95% CI=0.05-0.31, P < 0.001; OR=0.10, 95% CI=0.03-0.33, P < 0.001). We confirmed the robustness of these findings by showing significant associations of the haplotypes with risk in two randomly selected equal sized groups of cases and controls and, using the false positive report probability (FPRP) approach (FPRP values < 0.001 and < 0.004, respectively). A156-A312 was similarly associated with reduced risk in subgroups, including cases with no family history of skin cancer, with only BCC on the head/neck, and those with a high rate of increase in BCC numbers. The association was not dependent on gender, age, or extent of UVR exposure. A156-A312 was found in 6.3% of controls and the corresponding risk haplotype, C156-G312 (OR=1.65, 95% CI=1.21-2.26, P=0.002) in 35.4% of controls. We interpret these data as showing that XPD SNP mediate susceptibility to BCC.

Adult↗
PubMed2004

Promoter polymorphisms of tumor necrosis factor-alpha are associated with risk of gastric mucosa-associated lymphoid tissue lymphoma.

Genes involved in regulating antimicrobial immunity and inflammation may modulate the risk of Helicobacter pylori-associated diseases. IL-1 and TNF-alpha are major cytokines detected in H. pylori-infected tissues. We aimed to determine the role of gene polymorphisms for these cytokines and their receptors in 2 distinct H. pylori-related gastric malignancies, adenocarcinoma (GAC) and maltoma. Genotyping for IL-1beta (-31 C/T, -511 C/T), TNF-alpha (-238 G/A, -308 G/A, -857 C/T, -863 C/A, -1031 T/C), TNFR1 (-383 A/C) and TNFR2 (196 G/T) was undertaken for 70 patients with maltoma and 204 patients with noncardia GAC and compared to 210 unrelated healthy controls. Genotype frequencies showed no differences among patients with GAC or maltoma and controls for IL-1beta, TNFR1 or TNFR2. The TNF-alpha -857 T variant was significantly underrepresented in maltoma compared to controls (6.4% vs. 14.3%, p = 0.018), conferring a 3-fold decrease in risk (OR = 0.33, 95% CI 0.15-0.75). Comparison of allele frequencies between GAC and controls failed to show any statistical significance for TNF-alpha polymorphisms. We concluded that TNF-alpha -857 T itself or a neighboring gene may modify the risk of maltoma. The differences in genetic background as well as divergent clinicopathologic features between GAC and maltoma support the notion that fundamental mechanistic differences exist in these 2 well-defined H. pylori-related malignancies.

Adenocarcinoma↗
PubMed1996

Are vitamin D receptor polymorphisms associated with bone mineral density? A meta-analysis.

Vitamin D receptor (VDR) polymorphisms have been strongly associated with bone mineral density (BMD) in some studies but not in others. We used a meta-analytic approach to assess quantitatively the association between VDR and BMD and to examine the influence of specific study characteristics (e.g., skeletal site, mean age of subjects, menopausal status) on the reported results. Sixteen papers published in peer-reviewed journals through July 1996 were included. We calculated the mean difference, percent difference, and effect size (mean difference divided by standard deviation), comparing BMD between homozygous genotypes. At the hip, BMD in the BB genotype was lower than in the bb genotype (mean difference, -0.02 g/cm2; percent difference, -2.4% and effect size -0.18; p = 0.032). At the spine, the mean difference was -0.03 g/cm2; percent difference, -2.5%; and effect size, -0.19; p = 0.062. At the distal radius, the VDR effect was estimated as the mean difference, -0.01 g/cm2; percent difference, -1.7%; and effect size, -0.16; p = 0.078. The spine measurements exhibited the greatest between- and within-study variability. The difference in hip BMD between genotypes was larger (i.e., a more negative number) among the younger women and seemed to decrease with increasing age. However, statistical evidence for this trend was weak (p = 0.06). Data from the spine and the radius showed no evidence of a comparable interaction of the VDR effect with age. When we omitted data from the first report of an association between VDR polymorphisms and BMD, our analyses gave similar results, although the overall effect estimates were smaller. In the combined data from 29 study groups, the BB genotype frequency was 17.2, 4.9, and 2.3% in studies of whites, blacks, and Asians, respectively. VDR polymorphisms represent one genetic factor affecting BMD, but further research into the mechanisms, clinical significance, and its relation between other genetic and environmental factors is needed.

Adult↗
PubMed1992

Polymorphisms at the GLUT1 (HepG2) and GLUT4 (muscle/adipocyte) glucose transporter genes and non-insulin-dependent diabetes mellitus (NIDDM).

In order to determine the possible contribution of the GLUT1 (HepG2) glucose transporter gene to the inheritance of non-insulin-dependent diabetes mellitus (NIDDM), two restriction fragment length polymorphisms (RFLPs) and the related haplotypes at this locus were studied in 48 Italian diabetic patients and 58 normal subjects. Genotype frequencies for the XbaI polymorphism were significantly different between patients and controls (XbaI: chi 2 = 9.80, df = 2, P less than 0.0079). A significant difference was also found in the allele frequencies between NIDDM patients and controls (chi 2 = 9.39, df = 1, P less than 0.0022), whereas no differences were found for the StuI RFLP. No linkage disequilibrium was detected between the XbaI and StuI RFLPs in this sample. The analysis of the four haplotype frequencies (X1S1, X1S2, X2S1, X2S2) revealed a significant difference between diabetic patients and controls (chi 2 = 14.26, df = 3, P less than 0.002). By comparing single haplotype frequencies, a significant difference between the two groups was found for the X1S1 and X2S2 haplotypes. A two-allele RFLP at the GLUT4 (muscle/adipocyte) glucose transporter gene, detected with the restriction enzyme KpnI, was also examined; no differences were found between patients and controls for this RFLP. The finding of an association between polymorphic markers at the GLUT1 transporter and NIDDM suggests that this locus may contribute to the inherited susceptibility to the disease in this Italian population.

Adipose Tissue↗
PubMed1995

Dutch Caucasian population data on the loci LDLR, GYPA, HBGG, D7S8, and GC.

To introduce the loci LDLR, GYPA, HBGG, D7S8, and GC (PM loci) in Dutch forensic identity testing, allele and genotype frequencies were determined in a Dutch Caucasian population sample, which had previously been typed for the HLADQA1 locus [12]. All 6 loci met Hardy-Weinberg equilibrium expectations, and there is little evidence for association between pairs of loci. The combined power of discrimination for all 6 loci is 0.9997. The allele frequencies of the PM loci were similar to 2 other Caucasian populations [3, 10], and differed from 3 non-Caucasian populations [3].

Alleles↗
PubMed2000

Identification of two polymorphisms in the early growth response protein-1 gene: possible association with lipid variables.

Early growth response factor (EGR)-1 may play an important role in the development of atherosclerosis by inducing the expression of several relevant genes which contribute to the complex modulation of vascular structure and function, leading to vascular occlusive lesions. To investigate the possible role of molecular variants in the human EGR-1 gene for the predisposition to atherosclerosis or coronary heart disease we screened the 5'- and 3'- flanking regions and the entire coding sequence for polymorphisms by polymerase chain reaction/single-strand conformation polymorphism analysis and sequencing. Male patients (n=615) with myocardial infarction and 720 age-matched, male control subjects of the Etude Cas-Témoin de l'Infarctus du Myocarde were genotyped for two newly identified polymorphisms in the 5'- (C-151T) and 3'- (T+861C) flanking region of the EGR-1 gene using hybridization with allele-specific oligonucleotides. Allele and genotype frequencies did not significantly differ between patients with myocardial infarction and control subjects without coronary heart disease. In controls not taking hypolipidemic drugs there was a significant association of the -151T allele with lower plasma levels of total cholesterol (P=0.029), low-density lipoprotein cholesterol (P=0.025) and apolipoprotein B (P=0.038) and a higher ratio of high-density to low-density lipoprotein (P=0.049) than with the C-151 allele. We conclude that the C-151T polymorphism of the EGR-1 gene may contribute to modifications of the lipid metabolism. Our findings need to be replicated in independent studies, and in vitro promoter studies should evaluate the functional consequence of the -151T allele, which disrupts a consensus core sequence for the ubiquitous transcription factor activator protein 4.

Adult↗
PubMed2005

Genetic polymorphism of CYP2C9 and CYP2C19 in a Bolivian population: an investigative and comparative study.

OBJECTIVE: Several reports of CYP2C genetic polymorphism demonstrate its potential clinical role in determining both inter-individual and inter-ethnic differences in drug efficacy. We estimated the distribution of CYP2C9 and CYP2C19 common variants in the Bolivian population (a South American population), and compared these data with those from Asian, African, Caucasian and Oceanian populations. METHODS: Genomic DNA was obtained from 778 unrelated healthy volunteers from Bolivia. The genotypic status of CYP2C9 and CYP2C19 was determined by means of polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Allelic and genotypic frequencies of CYP2C9 and CYP2C19 were determined for the Bolivian population, and comparison of the data with other ethnic groups revealed a lower CYP2C9*2 frequency (4.8%) than in Caucasians, but a higher frequency than in Asians; frequencies of CYP2C9*3 (3.0%) and CYP2C9 (0.4%) poor metabolizers (PMs) were similar to those seen in Asian populations. Frequencies of CYP2C19*2 (7.8%), CYP2C19*3 (0.1%), and CYP2C19 PMs (1.0%) in the Bolivian population were for the most part lower than in Caucasian, Asian, Oceanian and African populations. CONCLUSION: This is the first study to investigate a South American population for genetic polymorphism in the CYP2C subfamily. The Bolivian population differs from most other ethnic groups in the incidence of CYP2C9 and CYP2C19 common variants that might be influenced by its admixture characteristics.

Adolescent↗
PubMed2001

Angiotensin-converting enzyme genotype distribution in familial vesicoureteral reflux.

Vesicoureteric reflux (VUR) is known to occur in families. In siblings of index patients with VUR, there is a much higher incidence (16% to 46%) than in the general population. The renin-angiotensin system plays an important role in renal development. Recently, it has been reported that angiotensin-converting enzyme (ACE) I/D gene polymorphism is a risk factor for renal parenchymal damage in patients with congenital urological abnormalities. The aim of this study was to investigate the ACE I/D genotype pattern in familial VUR patients. Blood samples were obtained from 86 families in which two or more members had VUR. Samples of DNA were extracted from 407 blood samples (183 affected patients and 224 non-affected family members). To detect ACE I/D polymorphism, polymerase chain reaction (PCR) amplification was performed using specific primers for the ACE gene. PCR products were electrophoresed with 2% agarose gel containing ethidium bromide. Among 224 non-affected family members the ACE genotype distribution of DD, ID, and II was 23%; 56% and 21%, respectively. The ACE genotype distribution of 183 affected patients was 28%, 47% and 25%, respectively. There was no significant difference in ACE I/D distribution between affected patients and their non-affected families. Both the ACE genotype distribution of affected patients and that of non-affected family members were not significantly different from the previously reported genotype distribution of the normal Caucasian population. This study demonstrates that ACE genotype frequencies are similar in index patients with VUR and their unaffected siblings, thus suggesting that the ACE gene is not involved in the development of familial VUR.

Adolescent↗
PubMed2004

5HT-2C receptor polymorphism in suicide victims. Association studies in German and Slavic populations.

Sustainable observations suggest that suicidal behaviour by itself may have biological correlates, among which those related to the serotonergic synapse hold the key position. Based on the association of suicide and serotonergic dysfunction, it was proposed that genetic mechanisms affecting suicidal behaviour could be related to the alterations of the genes encoding the elements of 5HT synapse. The present study tested the association of the polymorphism in the serotonin 2C (5HT-2C) receptor coding region (Cys23Ser) with suicide commitment. Study was based on two independent samples, one of German (284 suicide victims versus 297 controls) and other of Slavic/Croatian (118 suicide victims versus 275 controls) ethnicity. No significant differences in allele or genotype frequencies between victims and controls were demonstrated. Results did not provide supporting evidence for the potential involvement of the investigated variants of 5HT-2C receptor in the susceptibility to suicide.

Adult↗
PubMed2004

Leukotriene-related gene polymorphisms in ASA-intolerant asthma: an association with a haplotype of 5-lipoxygenase.

A recent study has demonstrated the possible involvement of a leukotriene C4 synthase (LTC4S) gene polymorphism in ASA-intolerant asthma (AIA) in a Polish population, whereas no significant association was noted in other populations. To investigate the role of genetic polymorphism in AIA development, we screened single nucleotide polymorphisms (SNPs) of the key enzymes involved in arachidonate metabolism, and the cysteinyl leukotriene receptor 1 (CYSLTR1) in a large Korean population with AIA: 93 AIA and 181 ASA-tolerant asthma (ATA) patients, and 123 normal controls. The single-base extension method was used to genotype SNPs in 5-lipoxygenase (ALOX5, -1708G-->A, 21C-->T, 270G-->A, 1728G-->A), ALOX5-activating protein (ALOX5AP, 218A-->G), prostaglandin-endoperoxide synthase 2 (PTGS2, COX2, -162C-->G, 10T-->G, R228H, V511A), LTC4S (-444A-->C), and CYSLTR1 (927T-->C). Haplotype analyses were undertaken for the SNPs in ALOX5. No significant differences in allele and genotype frequencies of single SNPs were observed between the patient groups ( P>0.05). However, the frequency of the ALOX5-ht1[G-C-G-A] haplotype in the AIA group was significantly higher than its frequency in the ATA group with a probability ( P) of 0.01, odds ratio (OR) of 5.0, and 95% confidence interval (95%CI) of 1.54-17.9, and in the normal controls ( P=0.03, OR=4.5, 95%CI=1.1-18.4), by using a dominant model. These results suggest a lack of association between the ALOX5AP, PTGS2, LTC4S, and CYSLTR1 gene polymorphisms and the AIA phenotype in the Korean population. However, the possible involvement of ALOX5-ht1[G-C-G-A] in AIA development is suggested.

5-Lipoxygenase-Activating Proteins↗
PubMed2005

The DBH -1021 C/T polymorphism is not associated with alcoholism but possibly with patients' exposure to life events.

Two DBH polymorphisms were investigated in 114 Brazilian alcoholics of European descent and 233 controls. Personality and life events were also analyzed among alcoholics. No significant differences were observed in allele or genotype frequencies between alcoholics and controls. No association was detected between the polymorphisms and personality dimensions. Carriers of the -1021 T allele presented a higher number (F = 7.49; P = 0.007) of life events. This study provides a preliminary indication that the DBH -1021 C/T polymorphism influences the exposure to life events.

Alcoholism↗
PubMed2005

The prevalence of Apo E4 genotype and its relationship to bone mineral density in Hong Kong Chinese.

Apolipoprotein E (Apo E) polymorphism has been implicated in many chronic diseases, including Alzheimer disease and osteoporosis. Significant association of the Apo E4 allele to low bone mineral density (BMD) has been repeatedly reported. We here examined the Apo E genotype frequencies in the Chinese population (n = 692) and its relationship to BMD. A significantly lower frequency (a prevalence of 7%) of the E4 alleles was found in our Chinese subjects compared to that reported in Caucasians (14.7%) or in Japanese (11.7%). However, no significant association between the Apo E4 allele and BMD Z score was observed in our test subjects; this may be due to the rarity of the Apo E4 allele frequency in Chinese, which requires a larger sample size for detection of significant association. Significant associations detected between Apo E2 allele and BMD at the femoral neck in elderly women (P = 0.02) and at the spine in elderly men (P = 0.03) were in the opposite direction and thus regarded as false-positive results. It is concluded that the Apo E4 allele is rare in Chinese, and a larger population size is needed to see if Apo E4 is associated with BMD in Chinese.

Aged↗
PubMed2003

The C(-260)>T gene polymorphism in the promoter of the CD14 monocyte receptor gene is not associated with acute myocardial infarction.

CD surface molecules mediates cell activation and signaling. In particular, CD14 on blood monocytes mediate monocyte/macrophage activation by lipopolysaccharide. Lipopolysaccharide and its receptor, CD14, have been implicated in atherogenesis. It has been recently shown that a C(-260)T polymorphism in the promoter of the CD14 receptor may be a risk factor for coronary artery disease. Recently this association has been questioned because no increased risk was found with the T allele, even in the homozygous state. In the present study we investigated a possible association between the C(-260)T polymorphism in the CD14 promoter and acute myocardial infarction. Two hundred and thrteen patients with and acute myocardial infarction 213 healthy controls were included in the study. Genotype frequencies of the C(-260)T polymorphism in the CD14 promoter were determined by polimerase chain reaction and the amplified product was cleaved with HaeIII. The frequency of the T allele was not significantly different in patients compared with controls. In this study we were not able to detect differences of frequency of the allele T (-260) in the promoter of the CD14 receptor gene in survivors of myocardial infarction and controls.

Cytosine↗
PubMed1984

The microdistribution of isoenzymic strains of Trypanosoma cruzi in southern Bolivia; new isoenzyme profiles and further arguments against Mendelian sexuality.

132 Trypanosoma cruzi stocks were collected in southern Bolivia (99 stocks in Tupiza, 33 in Tarija), and were characterized using five enzymes (six loci). From these 132 stocks, a sample of 21 was studied using 10 enzymes (12 loci) to establish the genetic distances between them. Only five different isoenzymic strains were registered among the 132 stocks: the taxonomic status of these strains is discussed. The distribution of the strains indicated that a Founder effect was not a constant fact at the level of the house and of the suburb, but that a Founder effect was more apparent for greater geographical distances. All strains were transmitted sympatrically by the same vector Triatoma infestans. Genotype frequencies demonstrated the lack of Mendelian sexuality among stocks of T. cruzi from southern Bolivia, confirming our previous results.

Alcohol Oxidoreductases↗
PubMed1996

Evaluation and usefulness of reverse dot blot DNA-PolyMarker typing in forensic case work.

Experiments were performed to evaluate the Amplitype PolyMarker DNA typing system for application to forensic casework. DNA extraction using chelex was compared with phenol-chloroform extraction for various biological materials including postmortem blood, blood samples used for alcohol quantification, fresh urine, envelopes and cigarette butts. Different amounts of genomic DNA were amplified to test the sensitivity of the Amplitype PM. Mixed samples of two different bloods were typed to determine the dilution at which mixtures could be detected. Different storage conditions were evaluated using urine samples. Postmortem blood samples were typed during 4 months to determine the effects of natural degradation. A population sample of 105 unrelated individuals from South-West Switzerland was analyzed and the genotype frequencies were compared with those reported by others. Finally, practical usefulness of the Amplitype PM system is illustrated by analysing casework samples. The results of this validation proved the great usefulness and sensitivity of the Amplitype PM system using the appropriate extraction and typing method. However, mixed samples had to be interpreted with caution owing to the possibility of non-specific alleles with stored material such as urine and postmortem blood.

Alleles↗