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Ronnen H Segman

Publications and source records attributed to Ronnen H Segman.

7 recordsLinked to original sources
PubMed2003

Attention deficit and hyperactivity disorder: review of genetic association studies.

Attention Deficit and Hyperactivity Disorder (ADHD) is a common idiopathic childhood neurodevelopmental disorder, exacting a significant clinical and public health toll. It impairs schooling and social adaptation, resulting in high rates of depression, conduct disorder, school dropouts, and substance abuse, and necessitating exposure of many children to prolonged courses of stimulant psychotropic medication. Although the biological basis of ADHD is unknown, it has been shown to possess considerable heritability. Candidate gene association studies proved to be a productive strategy leading to replicated association findings of genetic loci contributing to susceptibility to ADHD. Based on the mechanism of action of stimulant drugs effective in the alleviation of ADHD symptoms, current association studies have focused mainly on dopaminergic genes. Promising exploratory findings have also been reported for genes affecting other neurotransmitter systems. The current article reviews the rationale, methodology, and main findings in the field, and outlines future directions. Locating the actual genes mediating ADHD susceptibility will have far reaching implications for understanding the pathophysiology of ADHD as well as for understanding mechanisms of therapeutic drug action and genetic determinants of response.

Attention Deficit Disorder with Hyperactivity↗
PubMed2002

Angiotensin converting enzyme gene insertion/deletion polymorphism: case-control association studies in schizophrenia, major affective disorder, and tardive dyskinesia and a family-based association study in schizophrenia.

Angiotensin converting enzyme (ACE) is a candidate gene for psychiatric disorders. We examined the frequency of a functional insertion/deletion (I/D) polymorphism in the 16th intron of the ACE gene (located on chromosome 17q23) in groups of patients with schizophrenia (n = 104 and 113), major depression (n = 55), and bipolar disorder (n = 87) compared to healthy control subjects (n = 87). There was no evidence for allelic or genotypic association of the polymorphism with any of the disorders or with tardive dyskinesia (TD) in patients with schizophrenia. In a sample of nuclear families (n = 61) made up of one or more patients with schizophrenia recruited with their parents, there was no evidence for biased transmission of ACE I/D alleles. Particularly in the case of schizophrenia, these findings do not support an association of the ACE I/D polymorphism with the phenotypes examined.

Alleles↗
PubMed2002

Investigation of linkage and association/linkage disequilibrium of HLA A-, DQA1-, DQB1-, and DRB1-alleles in 69 sib-pair- and 89 trio-families with schizophrenia.

The hypothesis that HLA antigens confer susceptibility to schizophrenic disorders has been tested by studying linkage and association in a family sample with 69 sib-pair families. Suggestive evidence for linkage was obtained by nonparametric multipoint LOD score analysis with a maximum around DQB CAR (P = 0.0004), a microsatellite marker that is in linkage disequilibrium with the HLA antigen DQB1. Spurious evidence for negative association as calculated by the transmission disequilibrium test was found for HLA- DRB1*11 (chi-square = 11.72, corrected P value = 0.03) and for the haplotype DQB1*301-DQA1*501-DRB1*11 (chi-square = 11.3, corrected P value = 0.043). No evidence of association with these alleles was obtained in a sample of 89 trios with schizophrenic offspring and parents. Our results are not in favor of a direct involvement of the HLA system in development of schizophrenia, but are compatible with the possible existence of a susceptibility gene in the MHC region at chromosome 6p 21.31.

Alleles↗
PubMed2002

Positive association of dopamine D2 receptor polymorphism with bipolar affective disorder in a European Multicenter Association Study of affective disorders.

Convincing evidence for a genetic component in the etiology of affective disorders (AD), including bipolar affective disorder (BPAD) and unipolar affective disorder (UPAD), is supported by traditional and molecular genetic studies. Most arguments lead to the complex inheritance hypothesis, suggesting that the mode of inheritance is probably not Mendelian but most likely oligogenic (or polygenic) and that the contribution of genes could be moderate or weak. The purpose of the present European multicenter study (13 centers) was to test the potential role in BPAD and UPAD of two candidate dopaminergic markers, DRD2 and DRD3, using a case-control association design. The following samples were analyzed for DRD2: 358 BPAD/358 control (C) and 133 UPAD/ 133 C subjects, and for DRD3: 325 BPAD/ 325 C and 136 UPAD/136 C subjects. Patients and controls were individually matched for sex, age ( plus minus five years) and geographical origin. Evidence for significant association between BPAD and DRD2 emerged, with an over-representation of genotype 5-5 (P=0.004) and allele 5 (P=0.002) in BPAD cases compared to controls. No association was found for DRD2 in UPAD, and for DRD3 neither in BPAD or UPAD. Our results suggest that the DRD2 microsatellite may be in linkage disequilibrium with a nearby genetic variant involved in the susceptibility to BPAD. Our large European sample allowed for replicating of some previous reported positive findings obtained in other study populations.

Alleles↗
PubMed2002

Interactive effect of cytochrome P450 17alpha-hydroxylase and dopamine D3 receptor gene polymorphisms on abnormal involuntary movements in chronic schizophrenia.

BACKGROUND: Tardive dyskinesia is a chronic adverse effect of anti psychotic drugs, where association with a polymorphic site in the dopamine D3 receptor gene has been previously reported. Cytochrome P 450 17alpha-hydroxylase activity has been implicated with modulation of central dopamine release as well as neuroprotection. We investigated the association of a T -->C variation in the cytochrome P 450 17alpha-hydroxylase gene with tardive dyskinesia in patients with chronic schizophrenia. METHODS: Cytochrome P 450 17 allele and genotype frequencies were compared between matched schizophrenia patients with (n = 55) or without tardive dyskinesia (n = 58). Interactive effects of cytochrome P 450 17alpha-hydroxylase with the dopamine D3 Ser9Gly polymorphism on abnormal involuntary movements were examined. RESULTS: There was no difference in cytochrome P 450 17alpha-hydroxylase genotype distribution between patients with and without tardive dyskinesia; however, patients carrying the cytochrome P 450 17alpha-hydroxylase A2-A2 genotype and the dopamine D3gly allele had the highest orofacial (p <.04), distal (p <.05), and incapacitation (p <.04) scores on the Abnormal Involuntary Movements Scale. CONCLUSIONS: Schizophrenia patients who carry the dopamine D3gly allele and the cytochrome P 450 17alpha-hydroxylase A2-A2 genotype may be more likely to develop abnormal orofoacial and distal involuntary movements and to be incapacitated by these movements when chronically exposed to classical antipsychotic drugs.

Adult↗
PubMed2002

Pharmacogenetics of tardive dyskinesia: combined analysis of 780 patients supports association with dopamine D3 receptor gene Ser9Gly polymorphism.

Variability among individuals in their therapeutic response to psychotropic drugs and in susceptibility to adverse effects is considerable. Pharmacogenetics addresses the contribution of genetic factors to this variability. An important focus of interest in pharmacogenetics has been on candidate genes that play a role in susceptibility to the antipsychotic drug-induced adverse effect, tardive dyskinesia (TD). Four published studies have reported an association between a serine (ser) to glycine (gly) polymorphism in exon 1 of the dopamine D3 receptor gene (DRD3) and TD; three failed to replicate this finding and one found an insignificant trend. We examined the association in a pooled sample of 780 patients (317 with TD and 463 without TD) drawn from 6 research centers, who were divided into 8 groups based on their population origin. The analysis employed stepwise logistic regression so as to allow confounding effects of group, age, and gender to be taken into account. TD was significantly associated with DRD3 gly allele carrier status (x(2)=4.46, df 1, p =.04) and with DRD3 genotype (x(2)=6.62, df 2, p =.04) over and above the effect of group. Similar positive effects were observed when controlling for age and gender (x(2)=5.02, df 1, p =.02 for gly allele carrier status; x(2) = 7.51, df 2, p =.002 for genotype). Examining abnormal involuntary movement scores as a continuous variable, we found that patients homozygous for the gly allele had significantly higher scores than ser-gly heterozygotes (p =.006) or ser-ser homozygotes (p <.0001). We also performed a meta-analysis that included, besides the groups in the combined analysis, three other published studies on DRD3 and TD. The Mantel-Haenszel pooled odds ratio for DRD3 gly allele carrier status increasing susceptibility to TD was 1.33 (95% CI 1.04-1.70, p =.02); the cumulative pooled estimate showed an odds ratio of 1.52 (95% CI 1.08-1.68, p <.0001). These findings support a small but significant contribution of the DRD3 ser9gly polymorphism to TD susceptibility that is demonstrable over and above population effects and the effect of age and gender on the phenotype.

Adult↗