Underpowered repetitive transcranial magnetic stimulation might not be an effective antidepressant treatment.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
George Kirov
Publications and source records attributed to George Kirov.
The Bipolar Affective Disorder Dimension Scale (BADDS)--a dimensional scale for rating lifetime psychopathology in bipolar spectrum disorders.
BACKGROUND: Current operational diagnostic systems have substantial limitations for lifetime diagnostic classification of bipolar spectrum disorders. Issues include: (1) It is difficult to operationalize the integration of diverse episodes of psychopathology, (2) Hierarchies lead to loss of information, (3) Boundaries between diagnostic categories are often arbitrary, (4) Boundaries between categories usually require a major element of subjective interpretation, (5) Available diagnostic categories are relatively unhelpful in distinguishing severity, (6) "Not Otherwise Specified (NOS)" categories are highly heterogeneous, (7) Subclinical cases are not accommodated usefully within the current diagnostic categories. This latter limitation is particularly pertinent in the context of the increasing evidence for the existence of a broader bipolar spectrum than has been acknowledged within existing classifications. METHOD: We have developed a numerical rating system, the Bipolar Affective Disorder Dimension Scale, BADDS, that can be used as an adjunct to conventional best-estimate lifetime diagnostic procedures. The scale definitions were informed by (a) the current concepts of mood syndrome recognized within DSMIV and ICD10, (b) the literature regarding severity of episodes, and (c) our own clinical experience. We undertook an iterative process in which we initially agreed scale definitions, piloted their use on sets of cases and made modifications to improve utility and reliability. RESULTS: BADDS has four dimensions, each rated as an integer on a 0 - 100 scale, that measure four key domains of lifetime psychopathology: Mania (M), Depression (D), Psychosis (P) and Incongruence (I). In our experience it is easy to learn, straightforward to use, has excellent inter-rater reliability and retains the key information required to make diagnoses according to DSMIV and ICD10. CONCLUSIONS: Use of BADDS as an adjunct to conventional categorical diagnosis provides a richer description of lifetime psychopathology that (a) can accommodate sub-clinical features, (b) discriminate between illness severity amongst individuals within a single conventional diagnostic category, and (c) demonstrate the similarity between the illness experience of individuals who have been classified into different disease categories but whose illnesses both fall near the boundaries between the two categories. BADDS may be useful for researchers and clinicians who are interested in description and classification of lifetime psychopathology of individuals with disorders lying on the bipolar spectrum.
Bipolar Disorder↗
Strong evidence for association between the dystrobrevin binding protein 1 gene (DTNBP1) and schizophrenia in 488 parent-offspring trios from Bulgaria.
BACKGROUND: The gene encoding the dystrobrevin binding protein (DTNBP1) has been implicated in the pathogenesis of schizophrenia by several association studies. We tried to replicate these findings in a sample of 488 parent-proband trios recruited in Bulgaria. Probands had a diagnosis of schizophrenia (n = 441) or schizoaffective disorder (n = 47). METHODS: We genotyped eight single nucleotide polymorphisms within the gene, four of which had been reported in previous studies, and four identified as informative by our group through direct screening of the gene and genotyping in a sample of cases and control subjects. RESULTS: A significant excess of transmissions was observed for two of the markers, p1635 and p1757, (p =.0009 and.0013, respectively). Analysis of two-, three-, and four-marker haplotypes produced numerous positive results, with six (4% of the total combinations) at p <.001. CONCLUSIONS: These results provide strong support for DTNBP1 as a susceptibility gene for schizophrenia; however, different haplotypes seem to be associated in different studies.
Bulgaria↗
Support for RGS4 as a susceptibility gene for schizophrenia.
BACKGROUND: The gene encoding the regulator of G-protein signaling 4 has recently been associated with susceptibility to schizophrenia. This finding is particularly interesting, because it was replicated within the same study and also because there are functional, positional, and expression data to support the regulator of G-protein signaling 4 as a schizophrenia candidate gene. Although the original report was highly suggestive, a limitation was that the study was conducted on rather small samples. METHODS: We have examined a large case (n = 709) control (n = 710) sample for association between schizophrenia using four markers investigated in the earlier study, denoted single nucleotide polymorphisms 1, 4, 7, and 18. RESULTS: We were able to replicate the associations with single nucleotide polymorphisms 4 and 18 that had previously been reported individually and have also identified significant association with haplotypes constructed from single nucleotide polymorphisms 1 and 4. CONCLUSIONS: Our data give modest support for the hypothesis that the regulator of G-protein signaling 4 is a susceptibility gene for schizophrenia.
Adult↗
Lack of support for a genetic association of the XBP1 promoter polymorphism with bipolar disorder in probands of European origin.
Explore the source record for details and available documents.
Age of Onset↗
Family aggregation of high myopia: estimation of the sibling recurrence risk ratio.
PURPOSE: To estimate the sibling recurrence risk (KS) and the sibling recurrence risk ratio (lambda(S)) for high myopia in a cohort in the United Kingdom. METHOD: The recurrence risks for myopia and high myopia were estimated in the siblings of 296 randomly selected high myopes ascertained from an optometric practice population. A model using an age of onset of spectacle wear for myopia of 9.1 +/- 0.7 years or younger was developed as a surrogate for high myopia. The influence of parental myopia on the sibling recurrence risk for high myopia was also evaluated. RESULTS: KS was estimated (95% confidence limits) to be 10.0% (5.9, 14.8) and lambdaS to be 4.9 (2.8, 7.6). High myopes without myopic parents were surprisingly common ( approximately 40%) and were less likely to have highly myopic siblings (KS approximately 6%) than those with at least one myopic parent (KS approximately 14%). CONCLUSIONS: The sibling recurrence risk ratio reported herein (lambdaS approximately 4.9) implies that the high penetrance autosomal dominant loci for high myopia identified to date account for only a minority of cases of high myopia in the United Kingdom. Furthermore, high-penetrance autosomal dominant inheritance or even high-penetrance recessive inheritance, per se, cannot account for most cases of high myopia. Instead, it may be necessary to consider high myopia as a "complex disease" resulting from the influence of either alleles of reduced penetrance ("susceptibility genes"), environmental factors, or both.
Adolescent↗
Linkage analysis of the genetic loci for high myopia on 18p, 12q, and 17q in 51 U.K. families.
PURPOSE: To determine the extent to which high myopia in a cohort of 51 U.K. families can be attributed to currently identified genetic loci. METHODS: The families comprised 245 subjects with phenotypic information and DNA available, of whom 170 were classified as affected. Subjects were genotyped for microsatellite markers spanning approximately 40cM regions on 18p (MYP2), 12q (MYP3) and 17q, together with markers flanking COL2A1, COL11A1, and FBN1. Two-point linkage analyses were performed using the same disease gene segregation model as was used in the original publications, followed by nonparametric and multipoint analyses using Genehunter (http://linkage.rockefeller.edu/soft/gh/ provided in the public domain by Rockefeller University, New York, NY), with additional maximization over the parameter alpha, the proportion of linked families. RESULTS: Evidence of linkage was found for the MYP3 locus on 12q (two-point Zmax = 2.54, P = 0.0003 and multipoint hLOD = 1.08 at alpha = 0.24, P = 0.023 for marker D12S332; nonparametric linkage [NPL] = 1.49, P = 0.07 for marker D12S1607). For the 17q locus there was weak evidence of excess allele sharing and linkage under a recessive model (NPL = 1.34, P = 0.09 for marker D17S956; two-point hLOD = 1.24 at alpha = 0.30 for marker D17S1795; multipoint hLOD = 1.24 at alpha = 0.17, P = 0.014 for marker at 77.68 cM, between markers D17S956 and D17S1853). No significant linkage was found to the MYP2 locus on 18p, or to the COL2A1, COL11A1, and FBN1 genes. CONCLUSIONS: These results suggest that the MYP3 locus on 12q could be responsible for high myopia in approximately 25% of the U.K. families showing apparent autosomal dominant transmission, but that the loci on 18p and 17q are less common causes. Thus, additional loci for high myopia are likely to be the cause of the majority of cases of high myopia in the United Kingdom.
Chromosome Mapping↗
Association analysis of the HOPA12bp polymorphism in schizophrenia and manic depressive illness.
Variations in exon 42 of the HOPA (human opposite paired) gene have been associated with mental retardation, hypothyroidism and psychiatric disorders. We attempted to replicate the association with schizophrenia using 309 parent-offspring trios from Bulgaria and 367 unrelated cases and 368 blood donors from the UK. We also tested 125 bipolar trios from Bulgaria, 112 bipolar trios from the UK and a sample of 178 unrelated bipolar cases and 188 blood donors from the UK. The frequency of HOPA(12bp) in the 556 UK blood donors was 2.6% and it was not significantly different in the UK patients groups, where it ranged from 1.2 to 3.8%. Sixteen mothers transmitted the HOPA(12bp) allele to schizophrenic offspring, while 12 did not transmit, a non-significant difference. There was a trend for under-transmission of the rare allele to bipolar patients (T/NT = 4/10) and they had a lower rate of that allele than schizophrenic patients in the Bulgarian population (1% vs. 4.2%, P = 0.043). However the two diagnostic groups had similar allele frequencies in the UK populations: 2% versus 2.6%, P = 0.6. We conclude that the HOPA polymorphism is unlikely to be a major risk factor in the pathogenesis of these major psychiatric disorders although there could be a small effect in schizophrenia.
Alleles↗
Variation in the protocadherin gamma A gene cluster.
We screened for variation in the 12 protocadherin gamma A (PCDHGA) genes of the protocadherin cluster on chromosome 5q31. We used denaturing high-performance liquid chromatography followed by sequencing to identify changes in the DNA sequence. We identified 24 nonsynonymous changes, 24 synonymous SNPs, and 9 polymorphisms in the 5' flanking regions. The variant with the greatest predicted impact on the encoded protein was a frameshift polymorphism in PCDHGA8, caused by a deletion of one C base (Pro174fsdelC). The del variant was more common in 512 controls compared to 506 schizophrenic (SZ) cases (10.6% vs 7.2%, p=0.007) but this trend was not replicated in an independent sample of 403 trios, in which it was transmitted 47 times and not transmitted 55 times from heterozygous parents (p=0.43). We screened 10 of the common polymorphisms for association with schizophrenia by genotyping pooled DNA from 540 SZ cases and 540 controls, but none of them showed a significant difference. It will be important to identify the phenotype associated with the loss of the PCDHGA8 gene.
Amino Acid Sequence↗
Genetic variation in the seven-pass transmembrane cadherin CELSR1: lack of association with schizophrenia.
OBJECTIVES: Cadherins play a critical role in morphogenesis and maintenance of neuronal connections in the adult brain. We examined the gene encoding a member of the non-classic seven-pass transmembrane cadherins, CELSR1 for association with schizophrenia. It maps to chromosome 22q13.31, a region in which evidence for linkage to schizophrenia has been reported. The gene has an unusually large first exon of 3544 nucleotides, which encodes the signal peptide and all nine ectodomains in the protein. METHODS: We screened this exon in 24 schizophrenic patients using denaturing high-performance liquid chromatography followed by sequencing. Genotyping of amino-acid changes was performed with primer extension on a sample of 244 Bulgarian schizophrenic patients from 233 families and all their parents, as well as 180 schizophrenic patients from the UK and 157 controls. RESULTS: Three amino-acid changes were identified and shown to be in complete linkage disequilibrium: L556 V, S664W and R1126C. There was no preferential transmission of alleles from heterozygous parents to affected offspring. In the UK population the rare alleles were even more common in controls, and this difference almost reached statistical significance for R1126C (chi2=3.63, P=0.057). CONCLUSIONS: We conclude that variations in the nine ectodomains of CELSR1 do not increase susceptibility to schizophrenia.
Amino Acid Substitution↗
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↗
Universal, robust, highly quantitative SNP allele frequency measurement in DNA pools.
Detecting alleles that confer small increments in susceptibility to disease will require large-scale allelic association studies of single-nucleotide polymorphisms (SNPs) in candidate, or positional candidate, genes. However, current genotyping technologies are one to two orders of magnitude too expensive to permit the analysis of thousands of SNPs in large samples. We have developed and thoroughly validated a highly accurate protocol for SNP allele frequency estimation in DNA pools based upon the SNaPshot (Applied Biosystems) chemistry adaptation of primer extension. Using this assay, we were able to estimate the difference in allele frequencies between pooled cases and controls (Delta) with a mean error of 0.01. Moreover, when we genotyped seven different SNPs in a single multiplex reaction, the results were similar, with a mean error for Delta of 0.008. The assay performed well for alleles of low frequency alleles (f approximately 0.05) and was accurate even with relatively poor quality DNA template extracted from mouthwashes. Our assay conditions are generalisable, universal, robust and, therefore, for the first time, permit high-throughput association analysis at a realistic cost.
DNA↗
Major psychiatric disorders and the serotonin transporter gene (SLC6A4): family-based association studies.
The serotonin transporter (5-HTT) is a suitable candidate gene to test for involvement in the pathogenesis of major psychiatric disorders. We used the method of family-based controls to test for association between disease and a variable number tandem repeat (VNTR) in intron 2 of the gene, which has received support for involvement in the pathogenesis of several psychiatric disorders. We analysed 413 proband-parent trios of Bulgarian origin: 266 had a schizophrenic proband, 103 had a bipolar proband and 44 had a schizoaffective proband. The results were analysed using the extended transmission disequilibrium test. Possible effects of different alleles on certain clinical variables were examined by correlation analysis. Three alleles were detected: STin2.9, STin2.10 and STin2.12. None of the three diagnostic samples showed preferential transmission of alleles that reached conventional levels of statistical significance. We could not confirm previous results that STin2.12 allele increases susceptibility to bipolar disorder type I. The rare STin2.9 showed a non-significant trend for preferential transmission in the sample as a whole: 18 transmitted versus 11 non-transmitted (P = 0.2). The VNTR polymorphism in the 5-HTT gene does not appear to be a major risk factor for increasing susceptibility to major psychiatric disorders.
Adult↗
A functional polymorphism in the promoter of monoamine oxidase A gene and bipolar affective disorder.
The genes encoding for the enzymes monoamine oxidase (MAO) A and B are good candidates to investigate bipolar affective disorder. A 30 bp repeat in the MAOA promoter was recently demonstrated to be polymorphic and to affect transcriptional activity. In a family-based association design we found that none of the different repeat copies was preferentially transmitted from mothers (n = 131) to their children affected with bipolar disorder (chi(2) = 2.75, 4 d.f., p = 0.6). Following on our previous finding of an excess of low-activity genotypes of catechol-O-methyltransferase in patients with a rapid cycling form of illness, we examined for a similar trend with MAOA alleles. In an extended sample we found a non-significant trend for patients with an ultra-rapid cycling form of illness (n = 29) to have a higher frequency of low-activity alleles compared with 92 bipolar patients with a non-rapid cycling course of illness (chi(2) = 2.37, 1 d.f., p = 0.13).
Journal Article↗
Transcranial magnetic stimulation for patients with depression.
Transcranial magnetic stimulation (TMS) is a relatively new technique which has been used to treat depression. It delivers magnetic radiation to the head using a hand-held coil. Some studies have indicated clinical remission of depressive symptomatology with use of TMS. Methodological limitations remain, however, and more studies are recommended to determine its efficacy.
Depressive Disorder↗