Test of Xq26.3-28 linkage in bipolar and unipolar affective disorder in families selected for absence of male to male transmission

Identification of chromosome abnormalities in screening of a family with manic depression and psoriasis: predisposition to aneuploidy

Cytogenetic analysis is an important stage in understanding the genetic background of manic depression (MD), and may provide a valuable clue to the identification of target loci and successful search for major genes. In order to identify chromosomal regions we aimed to detect the relationships between chromosomal aberrations (CAs) and immunological markers in a family with MD and psoriasis. We used the cell cultivation and conventional G-banding. We found predominantly numerical aberrations. The most common aneuploidy was chromosome 8, followed by chromosome 22, 21, 15, X and Y. However, structural aberrations consisted of duplications, deletions, translocations and breaks, with a focus on: loci on del(1)(q12-q23), del(1)(q21.1-q24), del(1)(q21.1-q23), del(10)(p11.2-pter), der(2)t(2;4)(p25;p12), t(2;22)(p14;p13), t(19;Y)? and dup(10)(q26). The susceptibility genes of MD or psoriasis may be located on these loci. Numerical sex CAs included 4(5.8%) with 45,X, 3(4.3%) with 47,XXY, and 4(5.8%) with structural chromosome X; del(X)(q13); del(X)(p11-pter) del(X)(q21.3) and inv(Y)(q11.2). We also conducted an immunological study. According results of this study, the percentage of CD2+, CD4+ and CD8+ lymphocytes of the father were significantly higher, whereas CD4+ lymphocytes were decreased in the mother, when compared the healthy persons. The percentage of CD4 level of the son was decreased, whereas CD8+ lymphocytes were higher. The CD4/CD8 ratio of the father and the son was found to be significantly high. These results may suggest that MD and psoriasis have a significant impact on both genetic and immunological parameters.

The expression of folate sensitive fragile sites in patients with bipolar disorder

PURPOSE

Genetic factors are known to be important in the etiology of bipolar disorder (BD). The fragile sites (FSs) are a very interesting subject for the study of clinical disorders. The aim of this study was to evaluate fragile sites seen in patients with bipolar disorder and find a correlation between some fragile sites and bipolar disorder.

PATIENTS AND METHODS

The frequencies of folate sensitive FSs were compared in short-term whole blood cultures from bipolar patients and from normal individuals.

RESULTS

The rate of FS expression in the patients was considerably higher than in the controls (p < 0.001). Several chromosome regions including 1p36, 1q21, 1q32, 3p25, 7q22, 7q32, 11q23, 12q24, 13q32, 14q24, Xp22 and Xq26 were represented considerably more often in the patients than in the controls (p value between 0.001 to 0.036). Among these FSs, the sites 1p36, 1q21, 3p25, 7q22, 7q32, and 14q24 were not observed in other studies.

CONCLUSION

These regions can be the most active of hot spots in the genomes of bipolar patients, and may harbor important genes associated with BD.

An overview of the genetics of psychotic mood disorders

This article presents a conceptual review of the genetic underpinnings of psychotic mood disorders. Both unipolar and bipolar forms of mood disorder sometimes feature psychotic symptoms. Some evidence from epidemiological research suggests that psychotic forms of mood disorder specifically might be heritable. Linkage studies of mood disorders in general have also provided some support for that notion, as have associated studies involving serotonin and dopamine genes and psychotic mood disorder. Some research suggests there might be a genetic connection between schizophrenia and bipolar disorder, undermining the Kraepelinian dichotomous classification of the psychoses. Future research should continue to examine psychotic forms of mood disorder using both epidemiological and molecular approaches.

Genome scan of a second wave of NIMH genetics initiative bipolar pedigrees: chromosomes 2, 11, 13, 14, and X

As part of the on-going NIMH Genetics Initiative on Bipolar Disorder, we have ascertained 153 multiplex bipolar pedigrees and genotyped them in two waves. We report here the genome scan results for chromosomes 2, 11, 13, 14, and X in the second wave of 56 families. A total of 354 individuals were genotyped and included in the current analyses, including 5 with schizoaffective/bipolar (SA/BP), 139 with bipolar I disorder (BPI), 41 with bipolar II disorder (BPII), and 43 with recurrent unipolar depression (RUP). Linkage analyses were carried out with multi-point parametric and non-parametric affected relative pair methods using three different definitions of the affected phenotype: (model 1) SA/BP and BPI; (model 2) SA/BP, BPI, and BPII; and (model 3) SA/BP, BPI, BPII, and RUP. The best findings were on 11p15.5 (NPL = 2.96, P = 0.002) and Xp11.3 (NPL = 2.19, P = 0.01). These findings did not reach conventional criteria for significance, but they were located near regions that have been identified in previous genetic studies of bipolar disorder. The relatively modest but consistent findings across studies may suggest that these loci harbor susceptibility genes of modest effect in a subset of families. Large samples such as that being collected by the NIMH Initiative will be necessary to examine the heterogeneity and identify these susceptibility genes.

Ancient DNA in anthropology: methods, applications, and ethics

Anthropologists were quick to recognize the potential of new techniques in molecular biology to provide additional lines of evidence on questions long investigated in anthropology, as well as those questions that, while always of interest, could not have been addressed by more traditional techniques. The earliest ancient DNA studies, both within anthropology and in other fields, lacked rigorous hypothesis testing. However, more recently the true value of ancient DNA studies is being realized, and methods are being applied to a wide variety of anthropological questions. We review the most common methods and applications to date, and describe promising avenues of future research. We find that ancient DNA analyses have a valuable place in the array of anthropological techniques, but argue that such studies must not be undertaken merely to demonstrate that surviving DNA is present in organic remains, and that no such work should be performed before a careful consideration of the possible ethical ramifications of the research is undertaken.

Excess of allele1 for alpha3 subunit GABA receptor gene (GABRA3) in bipolar patients: a multicentric association study

The available data from preclinical and pharmacological studies on the role of gamma amino butyric acid (GABA) support the hypothesis that a dysfunction in brain GABAergic system activity contributes to the vulnerability to bipolar affective disorders (BPAD). Moreover, the localization of the alpha3 subunit GABA receptor GABRA3 gene on the Xq28, a region of interest in certain forms of bipolar illness, suggests that GABRA3 may be a candidate gene in BPAD. In the present study, we tested the genetic contribution of the GABRA3 dinucleotide polymorphism in a European multicentric case-control sample, matched for sex and ethnogeographical origin. Allele and genotype (in females) frequencies were compared in 185 BPAD patients and 370 controls. A significant increase of genotype 1-1 was observed in BPAD females compared to controls (P=0.0004). Furthermore, when considering recessivity of allele 1 (females with genotype 1-1 and males carrying allele 1), results were even more significant (P= 0.00002). Our findings suggest that the GABRA3 polymorphism may confer susceptibility to or may be in linkage disequilibrium with another gene involved in the genetic etiology of BPAD.

Association between a polymorphism in the pseudoautosomal X-linked gene SYBL1 and bipolar affective disorder

In the past decade, several chromosomal regions have been analyzed for linkage with bipolar affective disorder (BPAD). There have been conflicting results regarding the involvement of X-chromosomal regions in harboring susceptibility genes for BPAD. Recently, a new candidate gene (SYBL1) for BPAD has been described on Xq28. SYBL1, which maps to the Xq pseudoautosomal region (PAR), encodes a member of the synaptobrevin family of proteins involved in synaptic vesicle docking, exocytosis, and membrane transport. A subsequent case-control association study, including 110 US-American patients with BPAD and 119 unrelated controls, investigated a potential etiological role of a novel polymorphism (G-->C transversion) in a regulatory region of the SYBL1 gene. In this analysis, the C allele showed a statistical trend to be more frequent in males with BPAD than in respective controls (P=0.06). This finding prompted us to verify whether a similar effect was also present in a larger German sample of 164 unrelated patients with BPAD (148 patients with BP I disorder, 16 patients with BP II disorder) and 267 controls. We observed a significantly increased frequency of genotypes homozygous for the C allele in females with BPAD in comparison with controls (P=0.017). Thus, our data strengthen the role of the SYBL1 gene as a candidate gene for BPAD.

Analysis of the pseudoautosomal X-linked gene SYBL1in bipolar affective disorder: description of a new candidate allele for psychiatric disorders

The absence of father-to-son transmission has been observed in a subset of families with bipolar disorder (BPD), suggestive of a susceptibility gene on the sex-linked portion of the X chromosome. This is supported by some genetic linkage studies that have provided evidence for a susceptibility locus near Xq28. We have analyzed one candidate gene on Xq28, SYBL1, which maps to the Xq pseudoautosomal region (PAR). SYBL1 encodes a member of the synaptobrevin family of proteins that is involved in synaptic vesicle docking and membrane transport. Genes in the PAR generally escape X-chromosome inactivation and have an active homolog on the Y chromosome, which would result in an increase in same-sex concordance in paternal transmitted traits. However, SYBL1 is neither expressed on the Y chromosome nor the inactive X chromosome and would therefore be expected to show typical sex-linked transmission. We have screened SYBL1 for mutations that could be tested as candidate alleles in the development of BPD. Following single-strand conformation polymorphism (SSCP) analysis and DNA sequencing, four single nucleotide polymorphisms were detected: a silent mutation at codon 108, two intron mutations without any obvious biological significance, and a G-->C transversion in the polypyrimidine tract at the 3' splice acceptor site preceding exon 8. This polymorphism, which creates a perfect 16/16 stretch of pyrimidines, was analyzed in 110 patients with BPD not selected for sex-linked transmission and 119 control subjects. The results show a statistical trend toward an increase in the frequency of the C allele in males with BPD but not females. Males: chi(2) = 3.46, 1 df, p =.06; Females: chi(2) =.20, 1 df, p =.66.

Ultradian rapid cycling in prepubertal and early adolescent bipolarity is not in transmission disequilibrium with val/met COMT alleles

BACKGROUND

Prepubertal children and early adolescents with bipolar disorders (PEA-BP) who participate in the ongoing study "Phenomenology and Course of Pediatric Bipolar Disorders" have a high prevalence of ultradian (within 24-hour periods) rapid cycling. Based on a case-control finding reported in bipolar (BP) adults of an association between rapid and ultradian rapid cycling with the low-activity allele of catechol-O-methyltransferase (l-COMT), study of linkage and linkage disequilibrium of l-COMT in the PEA-BP population seemed warranted.

METHODS

Genotypes on a subset of the larger PEA-BP sample, for whom trio blood collection was complete (i. e., probands and both of their biological parents), were used to perform transmission disequilibrium tests (TDTs). Diagnoses were established from a comprehensive battery that included WASH-U-KSADS (Washington University Kiddie Schedule for Affective Disorders and Schizophrenia) given to both mothers and children and from consensus conferences. Probands with PEA-BP (N = 52) were 10.9 +/- 2.8 years old at index episode; had a mean age of BP onset at 8.0 +/- 3.8 years; were severely impaired, with a mean Children's Global Assessment Scale score of 44.5 +/- 8.9; and manifested the cardinal features of BP (84.6% had euphoric mood, 76.9% had grandiosity, and 57.7% had psychosis). Ultradian rapid cycling occurred in 75%. Genotyping of the single nucleotide polymorphism at COMT was performed using automated capillary electrophoresis single-strand conformational polymorphism with detection by laser-induced fluorescence.

RESULTS

Transmission disequilibrium tests were not significant for preferential transmission of l-COMT for the ultradian rapid-cycling subgroup or for the entire PEA-BP sample.

CONCLUSIONS

The lack of linkage disequilibrium between l-COMT and ultradian rapid cycling in the PEA-BP sample compared to reported findings of an association in case-control studies of adults is discussed in terms of age-specific developmentally relevant phenotypes, anticipatory mechanisms, and heterogeneity. Repeat TDT analyses after these PEA-BP probands reach their adult phenotypes will be informative.