Manic-depression genes and the new millennium: poised for discovery

Influencing factors for mental health of general practitioners in Hebei Province under the outbreak of COVID-19: A cross-sectional study

OBJECTIVE

This study aimed to understand the mental health status of general practitioners (GPs) in Hebei Province during the outbreak of coronavirus disease 2019, analyse influencing factors, and establish and evaluate the risk prediction model.

METHODS

During February 25-29, 2020, a self-designed questionnaire was used to conduct an online survey of GPs in Hebei Province. The survey included a questionnaire on GPs' basic information, a questionnaire on GPs' working hardware and software facilities, and a questionnaire on GPs' mental health condition. A total of 1040 participants returned the completely filled valid questionnaire, and the answers were analyzed using the χ² test, Wilcoxon rank-sum test and logistic regression with SPSS 20.0 software. Based on the results of binary logistic regression analysis, a risk prediction model was established, and the receiver operating characteristic curve was used to evaluate the model.

RESULTS

The results showed that 44.2% (460/1040) of GPs expressed anxiety after the outbreak. Absence of prescreening clinics, fever clinics or isolated observation rooms in primary medical institutions; persons in the administrative area required to be isolated; low sleep quality of GPs and less than 6 hours of sleep per day of GPs were risk factors affecting the mental health status of GPs. Also, epidemic-related training and adequate protective equipment were the protective factors for the mental health status of GPs.

CONCLUSION

The government should strengthen the infrastructure construction of community institutions, equip them with sufficient epidemic protection equipment, ensure the rest time of GPs and strengthen mental health training to ensure the mental and physical health of GPs.

A balanced translocation disrupting BCL2L10 and PNLDC1 segregates with affective psychosis

Affective psychoses are a group of severe psychiatric disorders, including schizoaffective disorder and bipolar I disorder, together affecting ∼1% of the population. Despite their high heritability, the molecular genetics and neurobiology of affective psychosis remain largely elusive. Here, we describe the identification of a structural genetic variant segregating with affective psychosis in a family with multiple members suffering from bipolar I disorder or schizoaffective disorder, bipolar type. A balanced translocation involving chromosomes 6 and 15 was detected by karyotyping and fluorescence in-situ hybridization (FISH). Using whole-genome sequencing, we rapidly delineated the translocation breakpoints as corresponding intragenic events disrupting BCL2L10 and PNLDC1. These data warrant further consideration for BCL2L10 and PNLDC1 as novel candidates for affective psychosis. © 2016 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc.

Complement factor H and susceptibility to major depressive disorder in Han Chinese

BACKGROUND

Accumulating evidence suggests that altered immunity contributes to the development of major depressive disorder (MDD).

AIMS

To examine whether complement factor H (CFH), a regulator of activation of the alternative pathway of the complement cascade, confers susceptibility to MDD.

METHOD

Expression analyses were tested in 53 unmedicated people with MDD and 55 healthy controls. A two-stage genetic association analysis was performed in 3323 Han Chinese with or without MDD. Potential associations between CFH single nucleotide polymorphisms and age at MDD onset were evaluated.

RESULTS

CFH levels were significantly lower in the MDD group at both protein and mRNA levels (P = 0.009 and P = 0.014 respectively). A regulatory variant in the CFH gene, rs1061170, showed statistically significant genotypic and allelic differences between the MDD and control groups (genotypic P = 0.0005, allelic P = 0.0001). Kaplan-Meier survival analysis showed that age at onset of MDD was significantly associated with the C allele of rs1061170 (log rank statistic χ(2) = 6.82, P = 0.009). The C-allele carriers had a younger age at onset of MDD (22.2 years, s.d. = 4.0) than those without the C allele (23.6 years, s.d. = 4.3).

CONCLUSIONS

CFH is likely to play an important role in the development of MDD. rs1061170 has an important effect on age at onset of MDD in Han Chinese and may therefore be related to early pathogenesis of MDD, although further study is needed.

A significant risk locus on 19q13 for bipolar disorder identified using a combined genome-wide linkage and copy number variation analysis

Background

The genetic background to bipolar disorder (BPD) has been attributed to different genetic and genomic risk factors. In the present study we hypothesized that inherited copy number variations (CNVs) contribute to susceptibility of BPD. We screened 637 BP-pedigrees from the NIMH Genetic Initiative and gave priority to 46 pedigrees. In this subsample we performed parametric and non-parametric genome-wide linkage analyses using ~21,000 SNP-markers. We developed an algorithm to test for linkage restricted to regions with CNVs that are shared within and across families.

Results

For the combined CNV and linkage analysis, one region on 19q13 survived correction for multiple comparisons and replicates a previous BPD risk locus. The shared CNV map to the pregnancy-specific glycoprotein (PSG) gene, a gene-family not previously implicated in BPD etiology. Two SNPs in the shared CNV are likely transcription factor binding sites and are linked to expression of an F-box binding gene, a key regulator of neuronal pathways suggested to be involved in BPD etiology.

Conclusions

Our CNV-weighted linkage approach identifies a risk locus for BPD on 19q13 and forms a useful tool to future studies to unravel part of the genetic vulnerability to BPD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13040-015-0076-y) contains supplementary material, which is available to authorized users.

Monoamine oxidase a gene polymorphisms and bipolar disorder in Iranian population

BACKGROUND

Bipolar disorder (BPD) is a common and severe mood disorder. Although genetic factors have important rolesin the etiology of bipolar disorder, no specific gene has been identified in relation to this disorder. Monoamine oxidase gene is suggested to be associated with bipolar disorder in many studies.

OBJECTIVES

This study aimed to investigatethe role of MAOA gene polymorphisms in the etiology of bipolar disorder in Iranian population.

PATIENTS AND METHODS

This study is a case-control study, with convenient sampling. Three common polymorphisms, a CA microsatellite, a VNTR, and a RFLP were typed in 156 bipolar patients and 173 healthy controls. Patients were chosen from Imam Hossein General Hospital, Psychiatry Ward (Tehran/Iran). Controlsamples for this study consisted of 173 healthy individuals recruitedby convenient sampling. Allelic distributions of these polymorphisms were analyzed in bipolar and control groups to investigate any association with MAOA gene.

RESULTS

Significant associations were observed regarding MAOA-CA (P = 0.016) and MAOA-VNTR (P = 0.004) polymorphisms in the bipolar females. There was no association between MAOA-RFLP and bipolar disorder.

CONCLUSIONS

The obtained results confirm some previous studies regardinga gender specific association of MAOA gene with the bipolar disorder.

Hypothesis of the neuroendocrine cortisol pathway gene role in the comorbidity of depression, type 2 diabetes, and metabolic syndrome

Depression, type 2 diabetes (T2D), and metabolic syndrome (MetS) are often comorbid. Depression per se increases the risk for T2D by 60%. This risk is not accounted for by the use of antidepressant therapy. Stress causes hyperactivation of the hypothalamic–pituitary–adrenal (HPA) axis, by triggering the hypothalamic corticotropin-releasing hormone (CRH) secretion, which stimulates the anterior pituitary to release the adrenocorticotropin hormone (ACTH), which causes the adrenal secretion of cortisol. Depression is associated with an increased level of cortisol, and CRH and ACTH at inappropriately “normal” levels, that is too high compared to their expected lower levels due to cortisol negative feedback. T2D and MetS are also associated with hypercortisolism. High levels of cortisol can impair mood as well as cause hyperglycemia and insulin resistance and other traits typical of T2D and MetS. We hypothesize that HPA axis hyperactivation may be due to variants in the genes of the CRH receptors (CRHR1, CRHR2), corticotropin receptors (or melanocortin receptors, MC1R-MC5R), glucocorticoid receptor (NR3C1), mineralocorticoid receptor (NR3C2), and of the FK506 binding protein 51 (FKBP5), and that these variants may be partially responsible for the clinical association of depression, T2D and MetS. In this review, we will focus on the correlation of stress, HPA axis hyperactivation, and the possible genetic role of the CRHR1, CRHR2, MCR1–5, NR3C1, and NR3C2 receptors and FKBP5 in the susceptibility to the comorbidity of depression, T2D, and MetS. New studies are needed to confirm the hypothesized role of these genes in the clinical association of depression, T2D, and MetS.

Genomewide interaction and enrichment analysis on antidepressant response

BACKGROUND

Genomewide association studies (GWASs) on antidepressant efficacy have yielded modest results. A possible reason is that response is influenced by other factors, which possibly interact with genetic variation. We used a GWAS model to predict antidepressant response, by including predictors previously known to affect response, such as quality of life (QoL). We also evaluated the association between genes, previously implicated in gene-environment (G × E) interactions, and response using an enrichment analysis.

METHOD

We examined a sample of 1426 depressed patients from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial: 774 responders, 652 non-responders and 418,865 single nucleotide polymorphisms (SNPs) were analysed. First, in a GWAS model, we investigated whether genetic variations interact with patients' levels of QoL to predict response, after controlling for demographic characteristics, severity and population stratification. Second, we conducted an enrichment analysis exploring whether candidate genes that have emerged from prior G × E interaction studies on depression are associated with treatment response.

RESULTS

The GWAS model, with QoL as a moderator, yielded one SNP (rs520210) associated with response in the NEDD4L gene (p = 3.64 × 10⁻⁸). In the Caucasian sample only, we observed a drop in significance for this SNP. The enrichment analysis showed that SNPs within serotonergic genes contained more significant markers that predicted response, compared with a random set of genes in the genome.

CONCLUSIONS

Our findings point to possible target genes, which are proposed for further independent replication. Our enrichment analysis provides further support, in a genomewide context, of the role of serotonergic genes in influencing antidepressant response.

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.

Functional assessment of a promoter polymorphism in S100B, a putative risk variant for bipolar disorder

Calcium-binding protein S100B has been implicated in the pathology of bipolar affective disorder (BPAD) and schizophrenia (SZ). S100B protein levels are elevated in serum of patients with both disorders compared to controls. We previously reported genetic association of a SNP in the promoter of S100B, rs3788266, with a psychotic form of BPAD. To test for genotypic effects of rs3788266 in vivo, S100B serum protein levels were measured in 350 Irish and German subjects of known S100B genotype. The functional effect of rs3788266 on S100B promoter activity was studied using the luciferase reporter system in U373MG glioblastoma and SH-SY5Y neuroblastoma cell lines. Allelic effects of rs3788266 on protein complex formation at the S100B promoter were investigated by an electrophoretic mobility shift assay. Higher mean serum S100B levels were associated with the risk G allele of rs3788266 in BPAD cases (P = 0.0001), unaffected relatives of BPAD cases (P < 0.0001) and unrelated controls (P < 0.0001). Consistent with the in vivo findings, luciferase gene expression was significantly increased in the presence of the G allele compared to the A allele in SH-SY5Y (P = <0.0001), and in U373MG (P = <0.0008) cell lines. The binding affinity of both SH-SY5Y and U373MG protein complexes for the S100B promoter was significantly stronger in the presence of G allele compared to the A allele promoter fragments. These data support rs3788266 as a functional promoter variant in the S100B gene where the presence of the G allele promotes increased gene expression and is associated with increased serum levels of the protein.

Fine mapping of candidate regions for bipolar disorder provides strong evidence for susceptibility loci on chromosomes 7q

Genomewide scans of bipolar disorder (BP) have not produced consistent linkage findings. Follow-up studies using enlarged samples and enhanced marker density can bolster or refute claims of linkage and pave the way to gene discovery. We conducted linkage and association analyses, using a ~3-cM density map of 10 candidate regions, in a large BP pedigree sample (865 individuals from 56 pedigrees). The candidate regions were identified in a previous 10-cM genome-wide scan using a subset of this sample (373 individuals from 40 pedigrees). The present sample consists of the expanded original pedigrees ("core" pedigrees) and 16 additional pedigrees. We obtained experiment-wide significant linkage on chromosome 7q34 (LOD score 3.53, P < 0.001), substantially stronger than that observed in the genome-wide scan. Support for linkage was sustained on chromosomes 2p13, 4q31, 8q13, 13q32, 14q21, and 17q11, though at a more modest level. Family-based association analysis was consistent with the linkage results at all regions with linkage evidence, except 4q an 8q, but the results fell short of statistical significance. Three of the previously implicated regions-9q31, 10q21 and 10q24-showed substantial reduction in evidence of linkage. Our results strongly support 7q34 as a region harboring susceptibility locus for BP. Somewhat lesser, yet notable support was obtained for 2p13, 4q31, 8q13, 13q32, 14q21, and 17q11. These regions could be considered prime candidates for future gene finding efforts.

An investigation of candidate regions for association with bipolar disorder

We performed a case-control study of 1,000 cases and 1,028 controls on 1,509 markers, 1,139 of which were located in a 8 Mb region on chromosome 6 (105-113 Mb). This region has shown evidence of involvement in bipolar disorder (BP) in a number of other studies. We find association between BP and two SNPs in the gene LACE1. SNP rs9486880 and rs11153113 (both have P-values of 2 × 10(-5)). Both P-values are in the top 5% of the distribution derived from null simulations (P = 0.02 and 0.01, respectively). LACE is a good candidate for BP; it is an ATPase. We genotyped 173 other markers in 17 other positional and/or functional loci but found no further evidence of association with BP.

Meta-analysis of FKBP5 gene polymorphisms association with treatment response in patients with mood disorders

The aim of our study was to assess the association between FKBP5 gene polymorphisms and treatment response in patients with mood disorders using a meta-analysis. Eight separate studies that included data from 2199 subjects were identified. Meta-analysis was performed for three FKBP5 gene polymorphisms (rs1360780, rs3800373, and rs4713916). A significant association of FKBP5 gene rs4713916 polymorphism and response rate was found in patients with mood disorders (Overall: A versus G: OR=1.28, 95%CI=1.06-1.53, P=0.01; GA+AA versus GG: OR=1.32, 95%CI=1.05-1.67, P=0.02. Caucasian: A versus G: OR=1.28, 95%CI=1.06-1.55, P=0.01; GA+AA versus GG: OR=1.33, 95%CI=1.04-1.70, P=0.02). However, we did not detect the association between FKBP5 gene rs1360780 and rs3800373 polymorphisms and treatment response in patients with mood disorders (P>0.05). This meta-analysis demonstrates that treatment response in patients with mood disorders is associated with FKBP5 gene rs4713916 polymorphism, but not rs1360780 and rs3800373.

Brain-derived neurotrophic factor as a biomarker for mood disorders: an historical overview and future directions

Mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BPD), are the most prevalent psychiatric conditions, and are also among the most severe and debilitating. However, the precise neurobiology underlying these disorders is currently unknown. One way to combat these disorders is to discover novel biomarkers for them. The development of such biomarkers will aid both in the diagnosis of mood disorders and in the development of effective psychiatric medications to treat them. A number of preclinical studies have suggested that the brain-derived neurotrophic factor (BDNF) plays an important role in the pathophysiology of MDD. In 2003, we reported that serum levels of BDNF in antidepressant-naive patients with MDD were significantly lower than those of patients medicated with antidepressants and normal controls, and that serum BDNF levels were negatively correlated with the severity of depression. Additionally, we found that decreased serum levels of BDNF in antidepressant-naive patients recovered to normal levels associated with the recovery of depression after treatment with antidepressant medication. This review article will provide an historical overview of the role played by BDNF in the pathophysiology of mood disorders and in the mechanism of action of therapeutic agents. Particular focus will be given to the potential use of BDNF as a biomarker for mood disorders. BDNF is initially synthesized as a precursor protein proBDNF, and then proBDNF is proteolytically cleaved to the mature BDNF. Finally, future perspectives on the use of proBDNF as a novel biomarker for mood disorders will be discussed.

Meta-analysis of BDNF Val66Met polymorphism association with treatment response in patients with major depressive disorder

The aim of our meta-analysis was to assess the association between BDNF Val66Met polymorphism and treatment response in patients with MDD. 8 studies that included data from 1115 subjects were identified. We tested two phenotypes: response rate and remission rate. OR was used as a measure of the effect of the association in a fixed/random effect model. Meta-analysis was performed for genotypes Met/Met versus Val/Val, Val/Met versus Val/Val, Met/Met versus Val/Met, Val/Met+Met/Met versus Val/Val, Met/Met versus Val/Val+Val/Met, and Met allele versus Val allele. When all groups were pooled, a significant association of Val/Met genotype and increased response rate was found in comparison to Val/Val in overall population (OR=1.66, 95%CI=1.07-2.57, P=0.02). In the subgroup analysis, similar result was shown in Asian population (OR=1.83, 95%CI=1.03-3.26, P=0.04), but not in Caucasian population. We didn't observe a significant association of BDNF Val66Met polymorphism with remission rate. This meta-analysis demonstrates the association between BDNF Val66Met polymorphism and treatment response in patients with MDD, and Val66Met heterozygous patients have a better response rate in comparison to Val/Val homozygote patients, especially in Asian population.

Genetic research into bipolar disorder: the need for a research framework that integrates sophisticated molecular biology and clinically informed phenotype characterization

Research into the genetic basis of bipolar disorder (BD) has reached a turning point. Genome-wide association studies (GWAS), encompassing several thousand samples, have produced replicated evidence for some novel susceptibility genes; however, the genetic variants implicated so far account for only a fraction of disease liability, a phenomenon not limited to psychiatric phenotypes but characteristic of all complex genetic traits studied to date. It appears that pure genomic approaches, such as GWAS alone, will not suffice to unravel the genetic basis of a complex illness like BD. Genomic approaches will need to be complemented by a variety of strategies, including phenomics, epigenomics, pharmacogenomics, and neurobiology, as well as the study of environmental factors. This review highlights the most promising findings from recent GWAS and candidate gene studies in BD. It furthermore sketches out a potential research framework integrating various lines of research into the molecular biological basis of BD.

Genome scan in sibling pairs with juvenile-onset mood disorders: Evidence for linkage to 13q and Xq

Mood disorders (bipolar and depressive disorders) in children and adolescents are associated with significant morbidity and mortality. Twin and family studies, for the most part, indicate higher familiality and heritability for mood disorders that onset in childhood/adolescence than those that onset in adulthood. To identify the genetic contribution to mood disorders that onset in childhood/adolescence, we performed a genome scan on 146 nuclear families from Hungary containing an affected proband and affected siblings. In total, the pedigrees contained 303 affected children: 146 probands, 137 siblings with a first episode of mood disorder before 14.9 years of age, and 20 siblings with onset of their first episode after 14.9 years of age but before the age of 18. The results of the genome scan using 405 microsatellite markers did not provide evidence for linkage at the recommended genome wide significance level for any novel loci. However, markers on two chromosomes, 13q and Xq, provided evidence for linkage in regions previously identified as linked to bipolar disorder in multiple studies. For the marker on chromosome 13q the peak non-parametric multipoint LOD score was at the marker D13S779 (LOD = 1.5, P = 0.004). On chromosome Xq, evidence for linkage was observed across a large region spanning two regions previously linked to bipolar disorder; Xq24 to Xq28, with a peak at marker TTTA062 (LOD 2.10, P = 0.0009) in Xq28. Results for these regions exceed the recommended P-value for a replication study of P < 0.01 and thus provide evidence for these two loci as contributing to mood disorders with juvenile onset.

A genome screen of 35 bipolar affective disorder pedigrees provides significant evidence for a susceptibility locus on chromosome 15q25-26

Bipolar affective disorder is a heritable, relatively common, severe mood disorder with lifetime prevalence up to 4%. We report the results of a genome-wide linkage analysis conducted on a cohort of 35 Australian bipolar disorder families which identified evidence of significant linkage on chromosome 15q25-26 and suggestive evidence of linkage on chromosomes 4q, 6q and 13q. Subsequent fine-mapping of the chromosome 15q markers, using allele frequencies calculated from our cohort, gave significant results with a maximum two-point LOD score of 3.38 and multipoint LOD score of 4.58 for marker D15S130. Haplotype analysis based on pedigree-specific, identical-by-descent allele sharing, supported the location of a bipolar susceptibility gene within the Z(max-1) linkage confidence interval of 17 cM, or 6.2 Mb, between markers D15S979 and D15S816. Non-parametric and affecteds-only linkage analysis further verified the linkage signal in this region. A maximum NPL score of 3.38 (P=0.0008) obtained at 107.16 cM (near D15S130), and a maximum two-point LOD score of 2.97 obtained at marker D15S1004 (affecteds only), support the original genome-wide findings on chromosome 15q. These results are consistent with four independent positive linkage studies of mood and psychotic disorders, and raise the possibility that a common gene for susceptibility to bipolar disorder, and other psychiatric disorders may lie in this chromosome 15q25-26 region.

Bipolar disorder in the Bulgarian Gypsies: genetic heterogeneity in a young founder population

We report the results of follow-up analyses of 12 genomic regions showing evidence of linkage in a genome-wide scan (GWS) of Gypsy families with bipolar affective disorder (BPAD). The Gypsies are a young founder population comprising multiple genetically differentiated sub-isolates with strong founder effect and limited genetic diversity. The BPAD families belong to a single sub-isolate and are connected by numerous inter-marriages, resulting in a super-pedigree with 181 members. We aimed to re-assess the positive GWS findings and search for evidence of a founder susceptibility allele after the addition of newly recruited subjects, some changes in diagnostic assignment, and the use of denser genetic maps. Linkage analysis was conducted with SimWalk2, accommodating the full complexity of pedigree structure and using a conservative narrow phenotype definition (BPAD only). Six regions were rejected, while 1p36, 13q31, 17p11, 17q21, 6q24, and 4q31 produced nominally significant results in both the individual families and the super-pedigree. Haplotypes were reconstructed and joint tests for linkage and association were done for the most promising regions. No common ancestral haplotype was identified by sequencing a strong positional and functional candidate gene (GRM1) and additional STR genotyping in the top GWS region, 6q24. The best supported region was a 12 cM interval on 4q31, also implicated in previous studies, where we obtained significant results in the super-pedigree using both SimWalk2 (P = 0.004) and joint Pseudomarker analysis of linkage and linkage disequilibrium (P = 0.000056). The size of the region and the characteristics of the Gypsy population make it suitable for LD mapping.

Association between depression and the Gln460Arg polymorphism of P2RX7 gene: a dimensional approach

The P2RX7 gene (coding for P2X7 purinergic receptor) has been suggested as a novel candidate gene for major depressive disorder (MDD) and bipolar disorder (BPD). The proposed risk allele (G-allele) of the rs2230912 polymorphism results in an amino acid change at the 460th position, marking this genetic variation a possibly functional one. Here we present a case-control analysis of 171 patients diagnosed with MDD or BPD and 178 controls, as well as a dimensional approach using the Hospital Anxiety and Depression Scale (HADS) for studying the Gln460Arg polymorphism of the P2RX7 gene as a genetic risk factor in depression. While case-control analysis did not show significant difference between the groups, a significant association was found between the P2RX7 polymorphism and the HADS scales in the clinical group (MANOVA P = 0.001). Both anxiety and depression scores increased as the number of G-allele increased in the genotype groups (ANOVA for HADS-anxiety: P = 0.01, HADS-depression: P < 0.001). A significant interaction of clinical status and the P2RX7 polymorphism was also found for the depression scale (MANOVA P = 0.025, subsequent ANOVA for anxiety: P = 0.252; depression: P = 0.002). Whereas patients with G-allele-present genotypes showed more elevated depression scores, level of depression in the control group was not affected by the P2RX7 genotype. In conclusion, case-control analysis did not reveal significant results, but using a symptom severity scale we could support the association between depressive disorder and the G-allele of the Gln460Arg polymorphism in the P2RX7 gene.

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.

Association analysis of monoamine oxidase A gene and bipolar affective disorder in Han Chinese

Background

Monoamine oxidase A (MAOA) is a mitochondrial enzyme involved in degrading several different biological amines, including serotonin. Although several pieces of evidence suggested that MAOA is important in the etiology of bipolar affective disorder (BPD), associations for markers of the MAOA gene with BPD were not conclusive and the association has not been investigated in Taiwanese population. This study was designed to illustrate the role of MAOA in the etiology of BPD in Han Chinese.

Methods

Two markers, a dinucleotide polymorphism in exon 2 and a functional uVNTR on the promoter of the MAOA gene, were used to study the genetic association in 108 unrelated patients with BPD and 103 healthy controls. Allelic distributions of two polymorphisms were analyzed and, caused the MAOA located at X chromosome, haplotype association was performed using haplotype unambiguously assigned in male participants.

Results

While no difference in allelic distributions of two MAOA polymorphisms was found, the risk haplotype 114S was associated with BPD in male patients (P = 0.03). The significance, however, was not found in female patients with 114S haplotype.

Conclusion

Results from this study suggest that MAOA may have a gender-specific and small effect on the etiology of BPD in Taiwan. Due to the limited sample size, results from this study need to be confirmed in replicates.

Gene and expression analyses reveal enhanced expression of pericentrin 2 (PCNT2) in bipolar disorder

BACKGROUND

DISC1 has been suggested as a causative gene for psychoses in a large Scottish kindred. PCNT2 has recently been identified as an interacting partner of DISC1. In this study, we investigated the role of PCNT2 in bipolar disorder, by gene expression analysis and genetic association study.

METHODS

By TaqMan real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), we examined the messenger RNA (mRNA) levels of PCNT2 in the postmortem prefrontal cortex of bipolar disorder (n = 34), schizophrenia (n = 31), and control subjects (n = 32), obtained from Stanley Array Collection. We also compared the mRNA levels of PCNT2 in the peripheral blood lymphocytes of bipolar disorder (n = 21), schizophrenia (n = 21), depression (n = 33), and control subjects (n = 57). For the association study, 23 single nucleotide polymorphisms (SNPs) were analyzed in 285 bipolar disorder patients and 287 age-and gender-matched control subjects, all of Japanese origin. The genotypes were determined by TaqMan assay.

RESULTS

Significantly higher expression of PCNT2 was observed in the brain samples of bipolar group, compared with the control (p = .001) and schizophrenia (p = .018) groups. In the peripheral blood lymphocytes also, a significantly higher expression of PCNT2 was observed in the bipolar group, compared with the control subjects (p = .043). However, none of the SNPs analyzed in our study showed a significant association with bipolar disorder; a weak tendency toward association was observed for two intronic SNPs.

CONCLUSIONS

Our findings suggest that elevated levels of PCNT2 might be implicated in the pathophysiology of bipolar disorder.

Meta-analysis of 12 genomic studies in bipolar disorder

Multiple genome-wide expression studies of bipolar disorder have been published. However, a unified picture of the genomic basis for the disease has not yet emerged. Genes identified in one study often fail to be identified in other studies, prompting the question of whether microarray studies in the brain are inherently unreliable. To answer this question, we performed a meta-analysis of 12 microarray studies of bipolar disorder. These studies included >500 individual array samples, on a range of microarray platforms and brain regions. Although we confirmed that individual studies showed some differences in results, clear and striking regulation patterns emerged across the studies. These patterns were found at the individual gene level, at the functional level, and at the broader pathway level. The patterns were generally found to be reproducible across platform and region, and were highly statistically significant. We show that the seeming discordance between the studies was primarily a result of the following factors, which are also typical for other brain array studies: (1) Sample sizes were, in retrospect, too small; (2) criteria were at once too restrictive (generally focusing on fold changes >1.5) and too broad (generally using p < 0.05 or p < 0.01 as criteria for significance); and (3) statistical adjustments were not consistently applied for confounders. In addition to these general conclusions, we also summarize the primary biological findings of the meta-analysis, focusing on areas that confirm previous research and also on novel findings.

Further support for association of the mitochondrial complex I subunit gene NDUFV2 with bipolar disorder

BACKGROUND

The nuclear-encoded mitochondrial complex I subunit gene, NDUFV2, has been implicated in the pathogenesis of bipolar disorder (BD) in Japanese by virtue of association of variants in its promoter with BD and decreased NDUFV2 messenger ribonucleic acid (mRNA) levels in B lymphoblasts (BLCL) in BD patients compared to controls. We sought to determine if these same changes occur in non-Japanese populations and, if so, their relationship to altered basal intracellular Ca(2+) ([Ca(2+)](B)) in BLCL from BD patients.

METHODS

Bipolar disorder patients and healthy subjects included 298 subjects of European Caucasian descent. The 5'-nuclease allelic discrimination TaqMan assay was used to detect selected single nucleotide polymorphisms (SNPs) in promoter, introns and 3'UTR regions, spanning the NDUFV2 gene. NDUFV2 mRNA levels and [Ca(2+)](B) in BLCLs were determined.

RESULTS

The A allele of the NDUFV2 SNP rs1156044 was significantly associated (Bonferroni-corrected) with BD (p = 0.013) but differed in allele (rs1156044 G allele) from that previously reported as associated with BD. There was a trend for elevated BLCL [Ca(2+)](B) associated with SNP rs977581 in BD patients, but NDUFV2 mRNA levels in BLCLs did not differ between patients and controls, nor represented genotypes.

CONCLUSIONS

While genetic variants of NDUFV2 may increase risk for BD, the role of its altered expression and the link to intracellular Ca(2+) abnormalities in BD remains equivocal.

Brain-derived neurotrophic factor and its receptor tropomyosin-related kinase B in the mechanism of action of antidepressant therapies

The focus of this review is to critically examine and review the literature on the role of brain-derived neurotrophic factor (BDNF) and its primary receptor, tropomyosin-related kinase B (TrkB), in the actions of pharmacologically diverse antidepressant treatments for depression. This will include a review of the studies on the regulation of BDNF and TrkB by different types of antidepressant drug treatments and animal in models of depression, as well as altered levels of BDNF and TrkB in the blood and postmortem brain of patients with depression. Results from clinical and basic studies have demonstrated that stress and depression decrease BDNF expression and neurogenesis and antidepressant treatment reverses or blocks these effects, leading to the neurotrophic hypothesis of depression. Clinical studies demonstrate an association between BDNF levels and several disorders, including depression, epilepsy, bipolar disorder, Parkinson's and Alzheimer's diseases. Physical activity and diet exert neurotrophic effects and positively modulate BDNF levels. A common single nucleotide polymorphism (SNP) in the BDNF gene, a methionine substitution for valine, is associated with alterations in brain anatomy and memory, but what role it has in clinical disorders is unclear. Findings suggest that early childhood events and adult stress produce neurodegenerative alterations in the brain that can eventually cause breakdown of information processing in the neuronal networks regulating mood. Antidepressant treatments elevate activity-dependent neuronal plasticity by activating BDNF, thereby gradually restoring network function and ultimately mood.

Bipolar disorder: how far are we from a rigorous definition and effective management?

Bipolar disorder is a pathological disturbance of mood, characterized by waxing and waning manic, depressive and, sometimes distinctly mixed states. A diagnosis of bipolar disorder can only be made with certainty when the manic syndrome declares itself. Most individuals who are diagnosed with this disorder will experience both poles of the illness recurrently, but depressive episodes are the commonest cause of morbidity and, indeed, of death by suicide. Twin, adoption and epidemiological studies suggest a strongly genetic aetiology. It is a genetically and phenotypically complex disorder. Thus, the genes contributing are likely to be numerous and of small effect. Individuals with bipolar disorder also display deficits on a range of neuropsychological tasks in both the acute and euthymic phases of illness and correlations between number of affective episodes experienced and task performance are commonly reported. Current self-report and observer-rated scales are optimized for unipolar depression and hence limited in their ability to accurately assess bipolar depression. The development of a specific depression rating scale will improve the assessment of bipolar depression in both research and clinical settings. It will improve the development of better treatments and interventions. Guidelines support the use of antidepressants for bipolar depression. With regard to the adverse effects of antidepressants for bipolar depression, double-blind, placebo-controlled data suggest that antidepressant monotherapy or the addition of a tricyclic antidepressant may worsen the course of bipolar disorder. Importantly, adjunctive psychotherapies add significantly (both statistically and clinically) to the efficacy of pharmacological treatment regimens. The successful management of bipolar disorder clearly demands improved recognition of bipolar disorder and effective long-term treatment for bipolar depression as well as mania.

Genetic variants in the DRD2 gene moderate the relationship between stressful life events and depressive symptoms in adults: cardiovascular risk in young Finns study

OBJECTIVE

To examine the potential moderating role of DRD2 polymorphism (rs1800497) in the association between stressful life events and depressive symptoms among young adults. Although stressful life events, such as divorce, unemployment, and serious illness in the family, are generally associated with negative health outcomes, including depressive symptoms, there are large individual differences in coping with such events. A number of studies suggest that variants in dopamine receptor genes, such as DRD2, are associated with depression but it is unclear if such variants also modify the association between life events and depression.

METHODS

We analyzed the prospective data on life events and depressive symptoms in 1992 and 2001 related to 1611 young adults (672 men and 939 women, aged 15-30 years at baseline) who participated in the ongoing population-based cardiovascular risk in young Finns study.

RESULTS

Occurrence of stressful life events was associated with increased risk of subsequent depressive symptoms in men and women. However, this association was seen only among those who carried A2/A2 (n = 872) genotype. No such association was detected in participants carrying A1/A1 or A1/A2 (n = 486) genotype.

CONCLUSION

DRD2 polymorphism moderates the effect of stressful life events on depressive symptoms and those who carry A2/A2 DRD2 genotypes may be more vulnerable than others.

Chromosomal fragile site expression in Turkish psychiatric patients

Chromosomal aberrations associated with psychiatric disorders may suggest regions in which to focus a search for genes predisposing to psychosis by a linkage strategy. Identification of these may be especially important given the unknown pathophysiology and the probable genetic heterogeneity of psychiatric disorders. In this study, the frequencies of folate sensitive fragile sites (FS) were compared among psychiatric disorders (e.g., schizophrenia, bipolar disorder, and other psychosis) and normal individuals. The rate of FS expression in the patients was considerably higher than in the controls. Sites 1p22, 1q21, 1q32, 2q31, 3p14, 3p25, 5q22, 5q31, 6p21, 6q21, 6q25, 7q22, 7q32, 8q22, 10q21, 11q23, 12q24, 13q32, 14q24, 16q22, 17q21, Xp22 and Xq26 were expressed more frequently in the patients. Thirty possible relevant chromosomal sites were identified in schizophrenia: 1q21, 1q32, 2p13, 2q21, 3p14, 3p25, 3q21, 5q22, 5q31, 6p21, 6q25, 6q26, 7q21, 7q22, 7q32, 8q22, 9q21, 10q21, 11q23, 12q24, 13q32, 14q24, 16q22, 17q21, Xp22, Xq22, and Xq26. Possible relevant sites were also identified in bipolar disorder: sites 1p36, 1q21, 1q32, 3p14, 3p25, 5q31, 7q22, 7q32, 11q23, 12q24, 13q32, 14q24, Xp22, and Xq26. Sites in the other psychosis group were: 1p22, 1p32, 1p36, 1q21, 1q32, 2q31, 3p14, 3p25, 5q31, 6p21, 6q21, 6q25, 6q26, 7q22, 7q32, 8q22, 10q21, 11q23, 12q13, 12q24, 13q32, 16q22, 16q24, 17q21 and Xq26. Among patient groups, there were significant differences in bands 1p32, 2p13, 2q21, 2q31, 3p14, 3p25, 5q31, 6q21, 6q26, 7q22, 7q32, 9q21, 11qq23, 12q13, 12q24, 16q24, and Xq22 between schizophrenic and bipolar patients. These regions were more frequently expressed in schizophrenic patients than in bipolar patients. The 1p22, 1p32, and 16q24 regions were significantly more frequently expressed in the other psychosis group than in the bipolar group. These interesting regions, which may harbor important genes for psychosis, have produced strong support for linkage in the majority of genome scan projects.

Diagnosing major depressive disorder VII: family history as a diagnostic criterion

Eliciting information about a patient's family history is a component of a standard diagnostic evaluation. Since depression runs in families, a question arises as to whether family history information should be considered when diagnosing depression. The text of DSM-IV indicates that a family history of a mood disorder should sometimes be considered when trying to distinguish between major depressive disorder and other conditions such as catatonic schizophrenia. The questions posed herein are how well family history of depression performs as a diagnostic criterion, and how its performance compares with the DSM-IV symptom criteria. One thousand eight hundred psychiatric outpatients were evaluated with a semistructured diagnostic interview as part of a research assessment infrastructure that has been embedded in the Rhode Island Hospital Department of Psychiatry outpatient practice. Family history diagnoses were based on information provided by the patient. The interview followed the guide provided in the Family History Research Diagnostic Criteria. We constructed a continuum of family history morbidity based on the number of first-degree family members with a history of depression and whether the family member was treated for their depression. Thus, we determined the presence or absence of the family history diagnostic criterion in different ways. Family history information was collected on 9763 first-degree relatives of 1776 patients. The sensitivity of the family history criterion was lower than each of the symptoms. Based on the broadest definition of the family history variable, the specificity was also lower than all other symptoms. Based on the narrowest definition (two or more family members who were treated for depression), the specificity was higher than all of the symptom criteria though sensitivity dropped to 15%. Overall, as a diagnostic criterion, a family history of depression did not perform as well as the DSM-IV symptom criteria. Consistent with the familial nature of depression, the family history variable performed better as a diagnostic criterion when considering diagnosis from a lifetime, rather than a current, perspective. This has implications for the future consideration of genetic markers as diagnostic criteria.

Use of phenotypic covariates in association analysis by sequential addition of cases

Optimal use of phenotype information is important in complex disease gene mapping. We describe a method, sequential addition, for the analysis of case-control data by taking into account of a quantitative trait that is measured in cases but not in controls. The method also provides an estimate of the best phenotype definition for future studies. We demonstrate proof of principle, using an example of incorporation of age-at-onset data into a study of a small sample for association between APOE and late-onset Alzheimer's disease. The sequential addition method finds evidence of association when conventional case-control methods fail. We also illustrate the use of the method for taking account of a dimensional measure of psychosis in a study of the schizophrenia susceptibility gene, dysbindin, in bipolar disorder.

Molecular genetics of bipolar disorder

Bipolar disorder (BPD) is an often devastating illness characterized by extreme mood dysregulation. Although family, twin and adoption studies consistently indicate a strong genetic component, specific genes that contribute to the illness remain unclear. This study gives an overview of linkage studies of BPD, concluding that the regions with the best evidence for linkage include areas on chromosomes 2p, 4p, 4q, 6q, 8q, 11p, 12q, 13q, 16p, 16q, 18p, 18q, 21q, 22q and Xq. Association studies are summarized, which support a possible role for numerous candidate genes in BPD including COMT, DAT, HTR4, DRD4, DRD2, HTR2A, 5-HTT, the G72/G30 complex, DISC1, P2RX7, MAOA and BDNF. Animal models related to bipolar illness are also reviewed, with special attention paid to those with clear genetic implications. We conclude with suggestions for strategies that may help clarify the genetic bases of this complex illness.

Genome-wide linkage scan in a large bipolar disorder sample from the National Institute of Mental Health genetics initiative suggests putative loci for bipolar disorder, psychosis, suicide, and panic disorder

We conducted a 9-cM genome scan in a large bipolar pedigree sample from the National Institute of Mental Health genetics initiative (1060 individuals from 154 multiplex families). We performed parametric and nonparametric analyses using both standard diagnostic models and comorbid conditions thought to identify phenotypic subtypes: psychosis, suicidal behavior, and panic disorder. Our strongest linkage signals (genome-wide significance) were observed on chromosomes 10q25, 10p12, 16q24, 16p13, and 16p12 using standard diagnostic models, and on 6q25 (suicidal behavior), 7q21 (panic disorder) and 16p12 (psychosis) using phenotypic subtypes. Several other regions were suggestive of linkage, including 1p13 (psychosis), 1p21 (psychosis), 1q44, 2q24 (suicidal behavior), 2p25 (psychosis), 4p16 (psychosis, suicidal behavior), 5p15, 6p25 (psychosis), 8p22 (psychosis), 8q24, 10q21, 10q25 (suicidal behavior), 10p11 (psychosis), 13q32 and 19p13 (psychosis). Over half the implicated regions were identified using phenotypic subtypes. Several regions - 1p, 1q, 6q, 8p, 13q and 16p - have been previously reported to be linked to bipolar disorder. Our results suggest that dissection of the disease phenotype can enrich the harvest of linkage signals and expedite the search for susceptibility genes. This is the first large-scale linkage scan of bipolar disorder to analyze simultaneously bipolar disorder, psychosis, suicidal behavior, and panic disorder.

Family, twin, adoption, and molecular genetic studies of juvenile bipolar disorder

Juvenile bipolar disorder (JBD) has been a subject of significant research and debate. Phenotypic differences between JBD and adult-onset bipolar disorder have led researchers to question whether or not similar neuropathologic mechanisms will be found. While much is known about the genetic and environmental contributions to the adult-onset phenotype, less is known about their contributions to JBD. Here, we review family, twin, adoption, and molecular genetic studies of JBD. Behavioral genetic data suggest both genetic and environmental contributions to JBD, while molecular genetic studies find linkage to age of onset of bipolar disorder to chromosomes 12p, 14q, and 15q. Additionally, changes associated with symptom age of onset have been recently reported in the brain-derived neurotrophic factor (BDNF) and glycogen synthase kinase 3-beta (GSK3-beta) genes. We contend that further progress in discovering the precise genetic and environmental contributions to JBD may depend on advances in phenotypic refinement, an increased appreciation of comorbid conditions, and more investigation of the longitudinal course of the disorder.

Combined analysis from eleven linkage studies of bipolar disorder provides strong evidence of susceptibility loci on chromosomes 6q and 8q

Several independent studies and meta-analyses aimed at identifying genomic regions linked to bipolar disorder (BP) have failed to find clear and consistent evidence of linkage regions. Our hypothesis is that combining the original genotype data provides benefits of increased power and control over sources of heterogeneity that outweigh the difficulty and potential pitfalls of the implementation. We conducted a combined analysis using the original genotype data from 11 BP genomewide linkage scans comprising 5,179 individuals from 1,067 families. Heterogeneity among studies was minimized in our analyses by using uniform methods of analysis and a common, standardized marker map and was assessed using novel methods developed for meta-analysis of genome scans. To date, this collaboration is the largest and most comprehensive analysis of linkage samples involving a psychiatric disorder. We demonstrate that combining original genome-scan data is a powerful approach for the elucidation of linkage regions underlying complex disease. Our results establish genomewide significant linkage to BP on chromosomes 6q and 8q, which provides solid information to guide future gene-finding efforts that rely on fine-mapping and association approaches.

Identification of a potential bipolar risk haplotype in the gene encoding the winged-helix transcription factor RFX4

The gene encoding the transcription factor RFX4 represents an excellent neurobiological and positional candidate gene for Bipolar disorder due to the potential involvement of RFX4 proteins in the regulation of circadian rhythms and the proximity of the locus to numerous linkage signals on chromosome 12q23. In this study we have sought to identify common variants within the gene, which might confer risk to the disease in our large UK Caucasian sample of Bipolar patients (676 DSMIV Bipolar I probands, 690 controls). RFX4 was screened for sequence variants and the LD block structure across the genomic region determined using 22 biallelic polymorphisms (minor allele frequency >or=0.1). Through analysis of 10 haplotype-tagging markers and using a two-stage approach (subset I: 347 cases, 374 controls; subset II: 329 cases, 316 controls), we identified a haplotype at rs10778502 and ss24735177, which showed nominally significant disease association in our full sample (haplotype-specific P=0.002, global P=0.017; subset I: haplotype-specific P=0.0002, global P=0.0008; subset II: haplotype-specific P=0.572, global P=0.109). Evidence for potential disease association with mutations across the RFX4 region came also from the analysis of the nearby microsatellite D12S2072 (empirical P=0.009 in our full sample). Investigation of RFX4 brain cDNA tagged by rs10778502 provided evidence for significant allelic differences in expression (P<0.001), where some of the variance was accounted for by the genotype at ss24735177. Our findings thus indicate the potential functional relevance of the associated haplotype and now require replication in independent samples.

The ecology of bipolar disorder: the importance of sleep

Although much of the emphasis in treating Bipolar Disorder patients is on pharmacotherapy, sleep loss is an important trigger for mania and plays an important role in the condition. The purpose of this paper is to fully explore the chronobiological, environmental, social, and genetic factors that contribute to the sleep disruption that is characteristic of mania and bipolar disorder. This review is important because sleep, chronobiology, and genetics are under-emphasized content areas in nursing education. As a result, many practicing nurses are unaware of the importance of sleep for mental health or what to teach patients to improve both the quality of their sleep and the management of their condition.

Linkage and candidate gene analysis of 14q22-24 in bipolar disorder: support for GCHI as a novel susceptibility gene

Using a collection of Irish sib-pair nuclear families, we previously obtained modest evidence of linkage implicating 14q22-24 in bipolar disorder (BPD). To follow-up on this preliminary finding, an extended linkage analysis was performed which employed thirteen microsatellite markers, spanning a total distance of 85 cM on 14q. Effectively, P-values <0.05 were observed for a region extending over 41.88 cM, with the marker D14S281 displaying a peak multipoint non-parametric lod (NPL) score of 2.72 and an associated P-value of 0.003. Support for this finding was also obtained from flanking markers indicating excess allele sharing at 14q22-24 in Irish bipolar sib-pairs. A web-based candidate gene search of 14q22-24 resulted in the selection of GTP cyclohydrolase I (GCHI), located 200 kb 3' of D14S281, as the best plausible candidate gene for involvement in BPD. GCHI is the rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin (BH(4)), a natural cofactor for tyrosine and tryptophan hydroxylases. These enzymes play an essential role in the biosynthesis of various hormones and neurotransmitters such as dopamine, noradrenaline, adrenaline, and serotonin. Numerous studies have also suggested that the clinical symptoms of depression might be related to a deficiency of BH(4). An association study between BPD and a novel single nucleotide polymorphism (SNP) in GCHI (G to A at position -959 bp, upstream of the ATG codon), is also presented here. This study revealed that the variant A allele is preferentially transmitted to BPI probands (chi(2) = 4.54, P = 0.033) suggesting that variants within GCHI may contribute to BPD in the Irish population.

Bipolar disorder and diabetes mellitus: epidemiology, etiology, and treatment implications

INTRODUCTION

Bipolar disorder (BD) is a highly prevalent and disabling condition with significant mortality risk from suicide and other unnatural causes. This ignominious description is alongside recent observations that the majority of excess deaths in BD are secondary to medical comorbidity. The medical burden in BD is associated with a clustering of risk factors (e.g., obesity, smoking, unhealthy dietary habits) and inadequate utilization of preventative and primary healthcare. Diabetes mellitus (DM) is also a prevalent multifactorial disease which imparts substantial illness burden. Preliminary investigations indicate that patients who suffer from BD with comorbid DM have a more severe course and outcome, lower quality of life, higher prevalence of medical comorbidity and higher cost of illness.

METHODS

We conducted a MedLine search of all English-language articles 1966-2004 using the key words: bipolar disorder, major depressive disorder, diabetes mellitus, glucose metabolism, mortality, overweight, obesity, body mass index. The search was supplemented with manual review of relevant references. Priority was given to randomized controlled data, when unavailable; studies of sufficient sample size are presented.

RESULTS

Subpopulations of BD patients should be considered at high risk for DM. The prevalence of DM in BD may be three times greater than in the general population.

CONCLUSIONS

Bipolar disorder populations may be an at-risk group for glucose metabolic abnormalities. Opportunistic screening and vigilance for clinical presentations suggestive of DM is encouraged.

Expression of mitochondria-related genes in lymphoblastoid cells from patients with bipolar disorder

OBJECTIVES

Several studies have suggested mitochondrial abnormality in bipolar disorder. We reported the association of mitochondrial complex I subunit gene, NDUFV2 at 18p11, with bipolar disorder. A decrease in the mRNA expression of this gene was found in patients with bipolar disorder compared with controls. However, it was unclear whether only the NDUFV2 gene exhibited the decreased expression level in bipolar disorder. The aim of this study was to clarify the association of other nuclear-encoded complex I subunit genes and mitochondria-related genes with bipolar disorder.

METHODS

We quantified the mRNA expression level of five nuclear-encoded mitochondrial complex I subunit genes located at the chromosomal regions linked with bipolar disorder other than NDUFV2, three complex IV subunit genes, and four mitochondrial transcription-related genes using a real-time quantitative reverse transcription polymerase chain reaction method in the lymphoblastoid cell lines from 21 patients with bipolar disorder and 11 controls.

RESULTS

Decreased mRNA expression in patients with bipolar I disorder compared with control subjects was found in most of the complex I subunit genes. In addition, decreased expression levels of these genes correlated with that of NDUFV2. No statistically significant alterations of mRNA expression levels were found between bipolar patients and controls among two of three complex IV subunit genes and all transcription-related genes.

CONCLUSIONS

Our study suggests that the decreased expression of NDUFV2 has a considerable effect on other subunit genes in the mitochondrial respiratory chain and presents further evidence of the biological significance of NDUFV2 in bipolar disorder.

A genome-wide search for risk genes using homozygosity mapping and microarrays with 1,494 single-nucleotide polymorphisms in 22 eastern Cuban families with bipolar disorder

Homozygosity mapping is a very powerful method for finding rare recessive disease genes in monogenic disorders and may also be useful for locating risk genes in complex disorders, late onset disorders where parents often are not available, and for rare phenotypic subgroups. In the present study, homozygosity mapping was applied to 24 persons with bipolar disorder from 22 inbred families. The families were selected irrespective of whether other affected family members were present or not. A genome wide screen using genotypes from only a single affected person in each family was performed using the AFFYMETRIX GeneChip HuSNP Mapping Assay, which contains 1,494 single nucleotide polymorphisms. At chromosome 17q24-q25 a parametric multipoint LOD score of 1.96 was found at WIAF-2407 and WIAF-2405. When analyzing 19 additional microsatellite markers on chromosome 17q the maximum parametric multipoint LOD score was 2.08, 1.5 cM proximal to D17S668. The present study replicates a recent significant linkage finding.

Genomewide scan for affective disorder susceptibility Loci in families of a northern Swedish isolated population

We analyzed nine multigenerational families with ascertained affective spectrum disorders in northern Sweden's geographically isolated population of Vasterbotten. This northern Swedish population, which originated from a limited number of early settlers approximately 8,000 years ago, is genetically more homogeneous than outbred populations. In a genomewide linkage analysis, we identified three chromosomal loci with multipoint LOD scores (MPLOD) >/=2 at 9q31.1-q34.1 (MPLOD 3.24), 6q22.2-q24.2 (MPLOD 2.48), and 2q33-q36 (MPLOD 2.26) under a recessive affected-only model. Follow-up genotyping with application of a 2-cM density simple-tandem-repeat (STR) map confirmed linkage at 9q31.1-q34.1 (MPLOD 3.22), 6q23-q24 (MPLOD 3.25), and 2q33-q36 (MPLOD 2.2). In an initial analysis aimed at identification of the underlying susceptibility genes, we focused our attention on the 9q locus. We fine mapped this region at a 200-kb STR density, with the result of an MPLOD of 3.70. Genealogical studies showed that three families linked to chromosome 9q descended from common founder couples approximately 10 generations ago. In this approximately 10-generation pedigree, a common ancestral haplotype was inherited by the patients, which reduced the 9q candidate region to 1.6 Mb. Further, the shared haplotype was observed in 4.2% of patients with bipolar disorder with alternating episodes of depression and mania, but it was not observed in control individuals in a patient-control sample from the Vasterbotten isolate. These results suggest a susceptibility locus on 9q31-q33 for affective disorder in this common ancestral region.