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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Schizophrenia patients demonstrate a deficiency in the filtering of sensory information, and one specific measure involves a response to the second of a pair of auditory stimuli. A neurophysiological measure of this consists of the electroencephalographic response to pairs of auditory signals, emitted fractions of a second apart. Schizophrenic patients and some of their unaffected relatives show a failure of inhibition of a second tone if it occurs 50 msec after the first. A recent genome scan indicated that the gating defect is linked to the alpha 7 neuronal nicotinic acetyl choline receptor gene on chromosome 15. We genotyped 5 schizophrenia families with a total of 96 subjects with a dinucleotide polymorphic marker located less than 120 kb from the first exon of the alpha 7 neuronal nicotinic acetylcholine receptor gene. Linkage analysis was undertaken using parametric and nonparametric statistical methods. The results of the parametric analysis showed negative lod scores under both narrow and broad diagnosis (lod = -3.6 and -4.8, respectively, at theta = 0), and dominant and recessive modes of transmission of the disease. Nonparametric analysis using GENEHUNTER produced nonsignificant NPL scores (NPL = -0.4 and -0.3 for broad and narrow diagnoses, respectively). In summary, we did not find any evidence that the alpha 7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. However, we have not been able to assess the P50 measures in these families.
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PMID:No evidence for linkage of the CHRNA7 gene region in Canadian schizophrenia families. 975 20

Eight multiplex Utah schizophrenia pedigrees were screened for linkage by applying a non-parametric linkage program, GENEHUNTER, using 30 chromosome 6 DNA markers. The overall maximum NPL score of the combined pedigrees was 1.50 (P = 0.079) at marker D6s281, located near the q terminus. The highest overall maximum NPL score for an individual pedigree was 2.81 (P = 0.043). In the chromosome 6p region, where numerous positive findings have been reported, we obtained no positive results.
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PMID:Analysis of chromosome 6 markers in eight Utah schizophrenia pedigrees. 980 Feb 18

The genome scan of the European-American schizophrenia families from the Human Genetics Initiative of the National Institute of Mental Health (NIMH) reported a suggestive linkage to chromosome 10p. Subsequently, Paterson and Petronis [1999] reported evidence for transmission ratio distortion on 10p to females. They suggested that transmission ratio distortion to females might have created spurious evidence for linkage to 10p. To address this issue, we reanalyzed our 10p data using only male-male affected sibling pairs. The two chromosome 10p markers that gave the most evidence for linkage in our prior report continued to show evidence for linkage: D10S1423 (NPL Z = 3.0, P = 0.001) and its neighbor D10S582 (NPL Z = 2.9, P = 0.002). These data suggest that our prior report of suggestive linkage of schizophrenia to markers on 10p cannot be attributed to the transmission ratio distortion to females reported by Paterson and Petronis. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:607-608, 1999.
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PMID:Suggestive linkage of chromosome 10p to schizophrenia is not due to transmission ratio distortion. 1058 77

A number of recent reports of linkage of markers on chromosome 10p to schizophrenia, and evidence for linkage in one study to bipolar affective disorder, provide encouragement for psychiatric genetics, after nonreplication of linkage findings at other chromosomal regions. The same region on chromosome 10 also demonstrates evidence for linkage to obesity, female alcoholism, and female type 1 diabetes. However, evidence for linkage can be confounded by the biological phenomenon of transmission ratio distortion. Transmission ratio distortion (also termed segregation distortion or meiotic drive) results in non-Mendelian segregation of alleles to live born offspring, and has not been investigated at the majority of loci for complex traits. We examined evidence for transmission ratio distortion using 40 Centre d'Etude du Polymorphisme Humain (CEPH) pedigrees across chromosome 10 using CEPH genotype data. Evidence for linkage of females to D10S211 was found (multipoint non-parametric linkage Z score [NPL] = 1.84, P = 0.040), while there was no linkage of this marker to male sex. The observation of possible transmission ratio distortion in females on chromosome 10p requires additional study, and may impact on the interpretation of positive linkage findings in this region. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:657-661, 1999.
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PMID:Transmission ratio distortion in females on chromosome 10p11-p15. 1058 1

Recent reports have strongly linked markers near the alpha-7 nicotinic cholinergic receptor subunit gene on human chromosome 15q13-q14 to a sensory gating deficit common in schizophrenics, and have shown positive though non-significant results linking this region to the primary phenotype of schizophrenia in a sample of North American families. We therefore tested for linkage between markers in this region of chromosome 15q and schizophrenia in a sample of 15 multiply affected and 5 single case families with schizophrenia drawn from the Bantu-speaking black population of South Africa. An initial replication using markers from the original study gave an affected-only LOD score maximum of 1.08 under a recessive model at Theta=0.00 for D15S1360, a dinucleotide polymorphism found on the same YAC as the alpha-7 receptor gene. Nonparametric affected-only multipoint analysis gave a Z-score of 1. 29, P=0.098, for D15S1360, and Z=1.45, p=0.075 for D15S118. We then increased the resolution of the map with an extended set of 20 markers. Again, two peaks were observed, with NPL scores of 1.81, p=0.037, at D15S1043 and 1.79 at D15S1360 and 1.80 at D15S1010, both p=0.037. Transmission disequilibrium testing of data from D15S1360 gave an allele-wise and genotype-wise chi(2) of 6.59, 2 df, p=0.037. Haplotype transmission disequilibrium testing using a restricted allele and haplotype set from D15S1043 and D15S1360 gave a global chi(2) of 10.647, 4 df, P=0.007, and a maximum chi(2) of 6.567, 1 df, P=0.004 for excess transmission of the 1.2 haplotype into affected offspring. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:196-201, 2000.
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PMID:Haplotype transmission disequilibrium and evidence for linkage of the CHRNA7 gene region to schizophrenia in Southern African Bantu families. 1089 97

The hypothesis that a gene for susceptibility to psychosis (specifically in the X-Y homologous class) is located on the sex chromosomes has been proposed. Such a gene would account for the excess of sex chromosome anomalous males and females in populations of patients with psychosis, a tendency towards concordance by sex within families, and sex differences associated with psychosis and its underlying brain pathology. In earlier studies we observed small positive LOD scores in Xp11, and in a more recent and larger cohort of 178 sibling pairs, a peak multipoint nonparametric LOD score of 1. 55 at the locus DXS8032 in Xq21. The present study with a new set of markers extended the cohort to 301 ill sibling pairs and their parents. Despite the increase in sample size, the LOD score did not increase. A peak NPL of 1.55 was observed at the locus DXS1068 in proximal Xp, a region remote from the previous report. Separating families into those who were more likely to have X chromosome inheritance (maternal with no male to male transmission) did not yield stronger findings. In spite of the evidence that psychosis is related to a sex-dependent dimension of cerebral asymmetry, it is concluded that no consistent linkage of schizophrenia to the X chromosome can be demonstrated. In the context of the general failure of replication of linkage in psychosis, the possibility that the genetic predisposition to psychosis is contributed to by epigenetic modification rather than variations in the nucleotide sequence has to be considered.
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PMID:Failure to establish linkage on the X chromosome in 301 families with schizophrenia or schizoaffective disorder. 1089 11

Evidence from epidemiological studies and segregation analysis suggests oligo- or polygenic inheritance in schizophrenia. Since model independent methods are thought to be most appropriate for linkage analysis in complex disorders, we performed a genome-wide autosomal screen in 71 families from Germany and Israel containing 86 independent affected sib-pairs with parental genotype information for statistical analysis strictly identity by descent. We genotyped 305 individuals with 463 markers at an average distance of approximately 10 cM genome-wide, and 1-2 cM in candidate regions (5q, 6p, q, 8p, 10p, 18p, 22q). The highest multipoint LOD scores (ASPEX) were obtained on 6p (D6S260, LOD = 2.0; D6S274, LOD = 2.2, MHC region, LOD = 2.15) and on 10p (D10S1714, LOD = 2.1), followed by 5q (D5S2066, LOD = 1.36), 6q (D6S271, LOD = 1.12; D6S1613, LOD = 1.11), 1q (D1S2675, LOD = 1.04), and 18p (broad disease model: D18S1116, LOD = 1.0). One hundred and thirty-three additional family members were available for some of the families (extended families) and were genotyped for these regions. GENEHUNTER produced a maximum NPL of 3.3 (P = 0.001) for the MHC region and NPL of 3.13 (P = 0.0015) for the region on 10p. There is support for these regions by independent groups. In genome-wide TDT analysis (sTDT, implemented in ASPEX), no marker passed the significance level of 0.0001 given by multiple testing, but nominal significance values for D10S211 (P = 0.03) and for GOLF (P = 0.0032) support further the linkage results on 10p and 18p. Our survey of 22 chromosomes identified candidate regions which should be useful to screen for schizophrenia susceptibility genes.
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PMID:A genome-wide autosomal screen for schizophrenia susceptibility loci in 71 families with affected siblings: support for loci on chromosome 10p and 6. 1112 94

In an attempt to identify susceptibility loci for bipolar affective disorder, we are currently conducting a systematic genome screen with highly polymorphic microsatellite markers at an average marker spacing of 10 cM in a series of 75 families, comprising 66 families from Germany, eight families from Israel, and one family from Italy. The families were ascertained through index cases with bipolar affective disorder. The distribution of diagnoses is as follows: 126 individuals with bipolar I disorder, 40 with bipolar II disorder, 14 with schizoaffective disorder of the bipolar type, 40 individuals with recurrent unipolar depression, 51 with a minor psychiatric diagnosis, and two individuals with a diagnosis of schizophrenia. One hundred and seventy-one individuals are unaffected. Here, we present results from chromosome 10. Linkage analyses using a total of 33 microsatellite markers with parametric and non-parametric methods provided evidence for linkage at chromosomal region 10q25--q26. The highest two-point LOD score (2.86, theta = 0.05) was obtained for D10S217 using a dominant genetic model and a broad definition of affection status. The GENEHUNTER program localized the putative susceptibility locus within a ca 15-cM interval between markers D10S1483 and D10S217 with a maximum NPL(all) score of 3.12 (P = 0.0013). Positive linkage findings that have been reported by two independent studies further support the hypothesis of a susceptibility gene for bipolar affective disorder on 10q25-q26.
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PMID:A possible susceptibility locus for bipolar affective disorder in chromosomal region 10q25--q26. 1132 7

Bipolar affective disorder is a severe mood disorder that afflicts approximately 1% of the population worldwide. Twin and adoption studies have indicated that genetic factors contribute to the disorder and while many chromosomal regions have been implicated, no susceptibility genes have been identified. In this present study, we undertook a 10 cM genome screen using 400 microsatellite markers in a large multigenerational bipolar pedigree consisting of 40 individuals, including six affecteds. We found strongest evidence for linkage to chromosome 13q14. A maximum NPL score of 4.09 (P = 0.008) was obtained between markers D13S1272 and D13S153 using GENEHUNTER. A maximum two-point LOD score of 2.91 (theta = 0.0) was found for marker D13S153 and a maximum three-point LOD score of 3.0 was obtained between markers D13S291 and D13S153 under a recessive model with 90% maximum age-specific penetrance and including bipolar I and unipolar individuals as affected. Several other markers in the region, D13S175, D13S218, D13S263, and D13S156 had two-point LOD scores greater than 1.5. These results meet the criteria for evidence of suggestive linkage. Haplotype analysis enabled us to narrow the likely disease region to a 6 cM region between markers D13S1272 and D13S1319, which contains the serotonin 2A receptor candidate gene. Two single nucleotide polymorphisms were identified in this gene but we did not detect any significant differences in allele frequency in a case-control sample. The region on chromosome 13q14-32 has previously been implicated in other bipolar and schizophrenia cohorts. Our results provide further support for the existence of a susceptibility locus on chromosome 13q14.
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PMID:A genome screen of a large bipolar affective disorder pedigree supports evidence for a susceptibility locus on chromosome 13q. 1144 23

We conducted a 10 cM linkage genome scan in a set of 20 American pedigrees (153 subjects), ascertained through probands with panic disorder (PD). Several anxiety disorders segregate in these families; they were diagnosed on the basis of Schedule for Affective Disorders and Schizophrenia interview. In this article, we describe results for panic disorder and agoraphobia, which are closely related, common, heritable anxiety disorders. This is the first complete linkage genome scan for agoraphobia and the third for PD. A total of 407 markers (389 autosomal, 18 X chromosome) were genotyped. Multipoint LOD score and NPL analysis were completed using GENEHUNTER2. For PD, two genomic regions meet criteria for suggestive linkage. One of these regions is on chromosome 1 (LOD score = 2.04). This region coincides with a region that generated a LOD score of 1.1 in a previous genome scan by Crowe et al. [2001: Am J Med Genet (Neuropsychiatr Genet) 105:105-109]. The other (LOD score = 2.01) is located on chromosome 11p and occurs at marker CCKBR, one of eight candidate genes examined. For agoraphobia, the most promising potential linkage was on chromosome 3 (NPL score = 2.75; P = 0.005). This was accounted for primarily by a single family that by itself generated an NPL score of 10.01 (P = 0.0039) and a LOD score of 2.10. These results provide initial evidence for a genetic locus on chromosome 3 that contributes to risk for agoraphobia. They also support suggestive linkage to two risk loci for panic disorder. Additional potential loci were identified with lesser statistical support; several of these were consistent with previously reported panic disorder linkage results. Overall, the results presented here suggest that PD and agoraphobia are complex traits that share some, but not all, of their susceptibility loci. Published 2001 Wiley-Liss, Inc.
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PMID:Linkage genome scan for loci predisposing to panic disorder or agoraphobia. 1149 73


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