Multigene profiles to guide the use of neoadjuvant chemotherapy for breast cancer: a Copenhagen Breast Cancer Genomics Study

Estrogen receptor (ER) and human epidermal growth factor 2 (HER2) expression guide the use of neoadjuvant chemotherapy (NACT) in patients with early breast cancer. We evaluate the independent predictive value of adding a multigene profile (CIT256 and PAM50) to immunohistochemical (IHC) profile regarding pathological complete response (pCR) and conversion of positive to negative axillary lymph node status. The cohort includes 458 patients who had genomic profiling performed as standard of care. Using logistic regression, higher pCR and node conversion rates among patients with Non-luminal subtypes are shown, and importantly the predictive value is independent of IHC profile. In patients with ER-positive and HER2-negative breast cancer an odds ratio of 9.78 (95% CI 2.60;36.8), P < 0.001 is found for pCR among CIT256 Non-luminal vs. Luminal subtypes. The results suggest a role for integrated use of up-front multigene subtyping for selection of a neoadjuvant approach in ER-positive HER2-negative breast cancer.

Absolute risks of self-harm and interpersonal violence by diagnostic category following first discharge from inpatient psychiatric care

BACKGROUND

Persons discharged from inpatient psychiatric services are at greatly elevated risk of harming themselves or inflicting violence on others, but no studies have reported gender-specific absolute risks for these two outcomes across the spectrum of psychiatric diagnoses. We aimed to estimate absolute risks for self-harm and interpersonal violence post-discharge according to gender and diagnostic category.

METHODS

Danish national registry data were utilized to investigate 62,922 discharged inpatients, born 1967-2000. An age and gender matched cohort study was conducted to examine risks for self-harm and interpersonal violence at 1 year and at 10 years post-discharge. Absolute risks were estimated as cumulative incidence percentage values.

RESULTS

Patients diagnosed with substance misuse disorders were at especially elevated risk, with the absolute risks for either self-harm or interpersonal violence being 15.6% (95% CI 14.9, 16.3%) of males and 16.8% (15.6, 18.1%) of females at 1 year post-discharge, rising to 45.7% (44.5, 46.8%) and 39.0% (37.1, 40.8%), respectively, within 10 years. Diagnoses of personality disorders and early onset behavioral and emotional disorders were also associated with particularly high absolute risks, whilst risks linked with schizophrenia and related disorders, mood disorders, and anxiety/somatoform disorders, were considerably lower.

CONCLUSIONS

Patients diagnosed with substance misuse disorders, personality disorders and early onset behavioral and emotional disorders are at especially high risk for internally and externally directed violence. It is crucial, however, that these already marginalized individuals are not further stigmatized. Enhanced care at discharge and during the challenging transition back to life in the community is needed.

Reversal of viral and epigenetic HLA class I repression in Merkel cell carcinoma

Cancers avoid immune surveillance through an array of mechanisms, including perturbation of HLA class I antigen presentation. Merkel cell carcinoma (MCC) is an aggressive, HLA-I-low, neuroendocrine carcinoma of the skin often caused by the Merkel cell polyomavirus (MCPyV). Through the characterization of 11 newly generated MCC patient-derived cell lines, we identified transcriptional suppression of several class I antigen presentation genes. To systematically identify regulators of HLA-I loss in MCC, we performed parallel, genome-scale, gain- and loss-of-function screens in a patient-derived MCPyV-positive cell line and identified MYCL and the non-canonical Polycomb repressive complex 1.1 (PRC1.1) as HLA-I repressors. We observed physical interaction of MYCL with the MCPyV small T viral antigen, supporting a mechanism of virally mediated HLA-I suppression. We further identify the PRC1.1 component USP7 as a pharmacologic target to restore HLA-I expression in MCC.

SSX2 promotes the formation of a novel type of intranuclear lamin bodies

SSX proteins are normally restricted to spermatogenic cells, but ectopic expression can be observed in many types of human cancer. We recently demonstrated that SSX family members may contribute to tumorigenesis by modifying chromatin structure and, in specific settings, compromise chromatin stability. Here, we used normal and tumorigenic breast epithelial cell line models to further study the effect of ectopic expression of SSX2 on nuclear organization. We show that SSX2 induces the formation of a novel type of nucleoplasmic lamin bodies. Ectopic expression of SSX2 in various breast epithelial cell lines led to the formation of a previously undescribed type of intranuclear bodies containing both A and B type lamins but no other components of the nuclear lamina. SSX2-expressing cells contained a highly variable number of lamin bodies distributed throughout the nuclear space. SSX2-mediated establishment of intranuclear lamin bodies could not be linked to previous molecular interactions of SSX proteins, including polycomb proteins and the Mediator complex, but was, however, dependent on S-phase progression. These results reveal a novel interaction between SSX2 and lamins in the nucleoplasmic space. They further suggest that SSX2 promotes the formation of chromatin neighborhoods supporting the organization of lamins into nuclear bodies. We speculate that this may have implications for the organization and functional regulation of chromatin in cancer cells. Our study contributes to the further understanding of the biology of SSX proteins in tumorigenesis.

Inverted CD8 T-Cell Exhaustion and Co-Stimulation Marker Balance Differentiate Aviremic HIV-2-Infected From Seronegative Individuals

HIV-2 is less pathogenic compared to HIV-1. Still, disease progression may develop in aviremic HIV-2 infection, but the driving forces and mechanisms behind such development are unclear. Here, we aimed to reveal the immunophenotypic pattern associated with CD8 T-cell pathology in HIV-2 infection, in relation to viremia and markers of disease progression. The relationships between pathological differences of the CD8 T-cell memory population and viremia were analyzed in blood samples obtained from an occupational cohort in Guinea-Bissau, including HIV-2 viremic and aviremic individuals. For comparison, samples from HIV-1- or dually HIV-1/2-infected and seronegative individuals were obtained from the same cohort. CD8 T-cell exhaustion was evaluated by the combined expression patterns of activation, stimulatory and inhibitory immune checkpoint markers analyzed using multicolor flow cytometry and advanced bioinformatics. Unsupervised multidimensional clustering analysis identified a cluster of late differentiated CD8 T-cells expressing activation (CD38+, HLA-DR^int/high), co-stimulatory (CD226+/-), and immune inhibitory (2B4+, PD-1^high, TIGIT^high) markers that distinguished aviremic from viremic HIV-2, and treated from untreated HIV-1-infected individuals. This CD8 T-cell population displayed close correlations to CD4%, viremia, and plasma levels of IP-10, sCD14 and beta-2 microglobulin in HIV-2 infection. Detailed analysis revealed that aviremic HIV-2-infected individuals had higher frequencies of exhausted TIGIT+ CD8 T-cell populations lacking CD226, while reduced percentage of stimulation-receptive TIGIT-CD226+ CD8 T-cells, compared to seronegative individuals. Our results suggest that HIV-2 infection, independent of viremia, skews CD8 T-cells towards exhaustion and reduced co-stimulation readiness. Further knowledge on CD8 T-cell phenotypes might provide help in therapy monitoring and identification of immunotherapy targets.

Progressive immune dysfunction with advancing disease stage in renal cell carcinoma

The tumor immune microenvironment plays a critical role in cancer progression and response to immunotherapy in clear cell renal cell carcinoma (ccRCC), yet the composition and phenotypic states of immune cells in this tumor are incompletely characterized. We performed single-cell RNA and T cell receptor sequencing on 164,722 individual cells from tumor and adjacent non-tumor tissue in patients with ccRCC across disease stages: early, locally advanced, and advanced/metastatic. Terminally exhausted CD8⁺ T cells were enriched in metastatic disease and were restricted in T cell receptor diversity. Within the myeloid compartment, pro-inflammatory macrophages were decreased, and suppressive M2-like macrophages were increased in advanced disease. Terminally exhausted CD8⁺ T cells and M2-like macrophages co-occurred in advanced disease and expressed ligands and receptors that support T cell dysfunction and M2-like polarization. This immune dysfunction circuit is associated with a worse prognosis in external cohorts and identifies potentially targetable immune inhibitory pathways in ccRCC.

The Cancer/Testis Antigen Gene VCX2 Is Rarely Expressed in Malignancies but Can Be Epigenetically Activated Using DNA Methyltransferase and Histone Deacetylase Inhibitors

Identification of novel tumor-specific targets is important for the future development of immunotherapeutic strategies using genetically engineered T cells or vaccines. In this study, we characterized the expression of VCX2, a member of the VCX/Y cancer/testis antigen family, in a large panel of normal tissues and tumors from multiple cancer types using immunohistochemical staining and RNA expression data. In normal tissues, VCX2 was detected in the germ cells of the testis at all stages of maturation but not in any somatic tissues. Among malignancies, VCX2 was only found in tumors of a small subset of melanoma patients and thus rarely expressed compared to other cancer/testis antigens such as GAGE and MAGE-A. The expression of VCX2 correlated with that of other VCX/Y genes. Importantly, we found that expression of VCX2 was inversely correlated with promoter methylation and could be activated by treatment with a DNA methyltransferase inhibitor in multiple breast cancer and melanoma cell lines and a breast cancer patient-derived xenograft. The effect could be further potentiated by combining the DNA methyltransferase inhibitor with a histone deacetylase inhibitor. Our results show that the expression of VCX2 can be epigenetically induced in cancer cells and therefore could be an attractive target for immunotherapy of cancer.

Remodeling and destabilization of chromosome 1 pericentromeric heterochromatin by SSX proteins

Rearrangement of the 1q12 pericentromeric heterochromatin and subsequent amplification of the 1q arm is commonly associated with cancer development and progression and may result from epigenetic deregulation. In many premalignant and malignant cells, loss of 1q12 satellite DNA methylation causes the deposition of polycomb factors and formation of large polycomb aggregates referred to as polycomb bodies. Here, we show that SSX proteins can destabilize 1q12 pericentromeric heterochromatin in melanoma cells when it is present in the context of polycomb bodies. We found that SSX proteins deplete polycomb bodies and promote the unfolding and derepression of 1q12 heterochromatin during replication. This further leads to segregation abnormalities during anaphase and generation of micronuclei. The structural rearrangement of 1q12 pericentromeric heterochromatin triggered by SSX2 is associated with loss of polycomb factors, but is not mediated by diminished polycomb repression. Instead, our studies suggest a direct effect of SSX proteins facilitated though a DNA/chromatin binding, zinc finger-like domain and a KRAB-like domain that may recruit chromatin modifiers or activate satellite transcription. Our results demonstrate a novel mechanism for generation of 1q12-associated genomic instability in cancer cells.

A functional genetic screen identifies the Mediator complex as essential for SSX2-induced senescence

The senescence response to oncogenes is believed to be a barrier to oncogenic transformation in premalignant lesions, and describing the mechanisms by which tumor cells evade this response is important for early diagnosis and treatment. The male germ cell-associated protein SSX2 is ectopically expressed in many types of cancer and is functionally involved in regulating chromatin structure and supporting cell proliferation. Similar to many well-characterized oncogenes, SSX2 has the ability to induce senescence in cells. In this study, we performed a functional genetic screen to identify proteins implicated in SSX2-induced senescence and identified several subunits of the Mediator complex, which is central in regulating RNA polymerase-mediated transcription. Further experiments showed that reduced levels of MED1, MED4, and MED14 perturbed the development of senescence in SSX2-expressing cells. In contrast, knockdown of MED1 did not prevent development of B-Raf- and Epirubicin-induced senescence, suggesting that Mediator may be specifically linked to the cellular functions of SSX2 that may lead to development of senescence or be central in a SSX2-specific senescence response. Indeed, immunostaining of melanoma tumors, which often express SSX proteins, exhibited altered levels of MED1 compared to benign nevi. Similarly, RNA-seq analysis suggested that MED1, MED4, and MED14 were downregulated in some tumors, while upregulated in others. In conclusion, our study reveals the Mediator complex as essential for SSX2-induced senescence and suggests that changes in Mediator activity could be instrumental for tumorigenesis.

Analysis of Mass Cytometry Data

The CyTOF system produces single cell protein expression data similar to that from flow cytometry, but with an increased number of features measured. Traditionally, analysis of these data is carried out using manual gating, but with the increased dimensionality, manual gating becomes a suboptimal analysis strategy in some cases. To address this, a number of data analysis tools for tasks such as clustering, differential abundance analysis, and visualization have been developed and made freely available. We here introduce some of the more popular tools for CyTOF analysis and exemplify their utility in a common analysis workflow.

The iPSYCH2012 case-cohort sample: new directions for unravelling genetic and environmental architectures of severe mental disorders

The Integrative Psychiatric Research (iPSYCH) consortium has established a large Danish population-based Case-Cohort sample (iPSYCH2012) aimed at unravelling the genetic and environmental architecture of severe mental disorders. The iPSYCH2012 sample is nested within the entire Danish population born between 1981 and 2005, including 1 472 762 persons. This paper introduces the iPSYCH2012 sample and outlines key future research directions. Cases were identified as persons with schizophrenia (N=3540), autism (N=16 146), attention-deficit/hyperactivity disorder (N=18 726) and affective disorder (N=26 380), of which 1928 had bipolar affective disorder. Controls were randomly sampled individuals (N=30 000). Within the sample of 86 189 individuals, a total of 57 377 individuals had at least one major mental disorder. DNA was extracted from the neonatal dried blood spot samples obtained from the Danish Neonatal Screening Biobank and genotyped using the Illumina PsychChip. Genotyping was successful for 90% of the sample. The assessments of exome sequencing, methylation profiling, metabolome profiling, vitamin-D, inflammatory and neurotrophic factors are in progress. For each individual, the iPSYCH2012 sample also includes longitudinal information on health, prescribed medicine, social and socioeconomic information, and analogous information among relatives. To the best of our knowledge, the iPSYCH2012 sample is the largest and most comprehensive data source for the combined study of genetic and environmental aetiologies of severe mental disorders.

Differential DNA methylation at birth associated with mental disorder in individuals with 22q11.2 deletion syndrome

Individuals with 22q11.2 deletion syndrome (DS) have an increased risk of comorbid mental disorders including schizophrenia, attention deficit hyperactivity disorder, depression, as well as intellectual disability. Although most 22q11.2 deletion carriers have the long 3-Mb form of the hemizygous deletion, there remains a large variation in the development and progression of psychiatric disorders, which suggests that alternative factors contribute to the pathogenesis. In this study we investigated whether neonatal DNA methylation signatures in individuals with the 22q11.2 deletion associate with mental disorder later in life. DNA methylation was measured genome-wide from neonatal dried blood spots in a cohort of 164 individuals with 22q11.2DS, including 48 individuals diagnosed with a psychiatric disorder. Among several CpG sites with P-value<10-6, we identified cg23546855 (P-value=2.15 × 10-7) mapping to STK32C to be associated with a later psychiatric diagnosis. Pathway analysis of the top findings resulted in the identification of several Gene Ontology pathways to be significantly enriched (P-value<0.05 after Benjamini-Hochberg correction); among them are the following: neurogenesis, neuron development, neuron projection development, astrocyte development, axonogenesis and axon guidance. In addition, we identified differentially methylated CpG sites in LRP2BP (P-value=5.37 × 10-8) to be associated with intellectual disability (F70-79), in TOP1 (P-value=1.86 × 10-7) with behavioral disorders (F90-98), in NOSIP (P-value=5.12 × 10-8) with disorders of psychological development (F80-89) and in SEMA4B (P-value=4.02 × 10-7) with schizophrenia spectrum disorders (F20-29). In conclusion, our study suggests an association of DNA methylation differences at birth with development of mental disorder later in life in 22q11.2DS individuals.

Risk of eating disorders in immigrant populations

OBJECTIVE

The risk of certain psychiatric disorders is elevated among immigrants. To date, no population studies on immigrant health have addressed eating disorders. We examined whether risk of eating disorders in first- and second-generation immigrants differs from native-born Danes and Swedes.

METHOD

All individuals born 1984-2002 (Danish cohort) and 1989-1999 (Swedish cohort) and residing in the respective country on their 10th birthday were included. They were followed up for the development of eating disorders based on out-patient and in-patient data.

RESULTS

The risks of all eating disorder types were lower among first-generation immigrants compared to the native populations: Incidence-rate ratio (95% confidence interval) was 0.39 (0.29, 0.51) for anorexia nervosa, 0.60 (0.42, 0.83) for bulimia nervosa, and 0.62 (0.47, 0.79) for other eating disorders in Denmark and 0.27 (0.21, 0.34) for anorexia nervosa, 0.30 (0.18, 0.51) for bulimia nervosa, and 0.39 (0.32, 0.47) for other eating disorders in Sweden. Likewise, second-generation immigrants by both parents were at lower risk, whereas those with only one foreign-born parent were not.

CONCLUSION

The decreased risk of eating disorders among immigrants is opposite to what has been observed for other psychiatric disorders, particularly schizophrenia. Possible explanations include buffering sociocultural factors and underdetection in health care.

Familial clustering and risk of groin hernia in children

Background

The hypothesis was that groin hernias are hereditary. This study was undertaken to establish the degree of familial clustering of groin hernias on a nationwide scale.

Methods

A register‐based cohort was created consisting of all children in Denmark whose parents were born in 1970 or later by the use of the Danish Civil Registration System. Within this cohort, all groin hernia operations were identified. To establish the risk estimates associated with a positive family history of groin hernia operation, information on groin hernia operations in fathers, mothers and siblings was also assessed.

Results

In the cohort of 408 381 persons, a total of 4966 were operated on for groin hernia (incidence rate 2·12 per 1000 person‐years at risk). A person with a mother who had undergone surgery for a groin hernia had an increased risk of 2·89 (95 per cent c.i. 2·48 to 3·34) of having a groin hernia operation; a person with a father operated on for a groin hernia had an increased risk of 1·75 (1·58 to 1·94); and a person with a sibling operated on for a groin hernia had an increased risk of 2·54 (2·17 to 2·96). The strongest association was seen between mothers who had been operated on for groin hernia and their daughters (increased risk 6·01, 95 per cent c.i. 4·53 to 7·80), compared with the risk in girls who did not have a mother who had undergone surgery for groin hernia.

Conclusion

Groin hernias are clustered in families, with the strongest relationship seen between mothers and their daughters.

Familial confounding of the association between maternal smoking during pregnancy and internalizing disorders in offspring

BACKGROUND

Maternal smoking has consistently been associated with multiple adverse childhood outcomes including externalizing disorders. In contrast the association between maternal smoking during pregnancy (MSDP) and internalizing (anxiety and depressive) disorders in offspring has received less investigation.

METHOD

We conducted a nationwide cohort study including 957635 individuals born in Denmark between 1991 and 2007. Data on MSDP and diagnoses of depression or anxiety disorders were derived from national registers and patients were followed up from the age of 5 years to the end of 2012. Hazard rate ratios (HRRs) were estimated using stratified Cox regression models. Sibling data were used to disentangle individual- and familial-level effects of MSDP and to control for unmeasured familial confounding.

RESULTS

At the population level, offspring exposed to MSDP were at increased risk for both severe depression [HRR 1.29, 95% confidence interval (CI) 1.22-1.36] and severe anxiety disorders (HRR 1.26, 95% CI 1.20-1.32) even when controlling for maternal and paternal traits. However, there was no association between MSDP and internalizing disorders when controlling for the mother's propensity for MSDP (depression: HRR 1.11, 95% CI 0.94-1.30; anxiety disorders: HRR 0.94, 95% CI 0.80-1.11) or comparing differentially exposed siblings (depression: HRR 1.18, 95% CI 0.75-1.89; anxiety disorders: HRR 0.87, 95% CI 0.55-1.36).

CONCLUSIONS

The results suggest that familial background factors account for the association between MSDP and severe internalizing disorders not the specific exposure to MSDP.

High loading of polygenic risk in cases with chronic schizophrenia

Genomic risk profile scores (GRPSs) have been shown to predict case-control status of schizophrenia (SCZ), albeit with varying sensitivity and specificity. The extent to which this variability in prediction accuracy is related to differences in sampling strategies is unknown. Danish population-based registers and Neonatal Biobanks were used to identify two independent incident data sets (denoted target and replication) comprising together 1861 cases with SCZ and 1706 controls. A third data set was a German prevalent sample with diagnoses assigned to 1773 SCZ cases and 2161 controls based on clinical interviews. GRPSs were calculated based on the genome-wide association results from the largest SCZ meta-analysis yet conducted. As measures of genetic risk prediction, Nagelkerke pseudo-R(2) and variance explained on the liability scale were calculated. GRPS for SCZ showed positive correlations with the number of psychiatric admissions across all P-value thresholds in both the incident and prevalent samples. In permutation-based test, Nagelkerke pseudo-R(2) values derived from samples enriched for frequently admitted cases were found to be significantly higher than for the full data sets (Ptarget=0.017, Preplication=0.04). Oversampling of frequently admitted cases further resulted in a higher proportion of variance explained on the liability scale (improvementtarget= 50%; improvementreplication= 162%). GRPSs are significantly correlated with chronicity of SCZ. Oversampling of cases with a high number of admissions significantly increased the amount of variance in liability explained by GRPS. This suggests that at least part of the effect of common single-nucleotide polymorphisms is on the deteriorative course of illness.

A population-based study of the risk of schizophrenia and bipolar disorder associated with parent-child separation during development

BACKGROUND

There is growing interest in the role of childhood adversities, including parental death and separation, in the etiology of psychotic disorders. However, few studies have used prospectively collected data to specifically investigate parental separation across development, or assessed the importance of duration of separation, and family characteristics.

METHOD

We measured three types of separation not due to death: maternal, paternal, and from both parents, across the ages of 1-15 years among a cohort of 985 058 individuals born in Denmark 1971-1991 and followed to 2011. Associations with narrowly and broadly defined schizophrenia and bipolar disorder in the psychiatric register were assessed in terms of separation occurrence, age of separation, and number of years separated. Interactions with parental history of mental disorder were assessed.

RESULTS

Each type of separation was associated with all three outcomes, adjusting for age, sex, birth period, calendar year, family history of mental disorder, urbanicity at birth and parental age. Number of years of paternal separation was positively associated with both schizophrenia and bipolar disorder. Associations between separation from both parents and schizophrenia were stronger when separation occurred at later ages, while those with bipolar disorder remained stable across development. The first occurrence of paternal separation appeared to increase risk more when it occurred earlier in childhood. Associations differed according to parental history of mental disorder, although in no situation was separation protective.

CONCLUSIONS

Effects of parental separation may differ by type, developmental timing and family characteristics. These findings highlight the importance of considering such factors in studies of childhood adversity.

Lack of ADAM2, CALR3 and SAGE1 Cancer/Testis Antigen Expression in Lung and Breast Cancer

Immunotherapy is emerging as a supplement to conventional cancer treatment, and identifying antigen targets for specific types of cancer is critical to optimizing therapeutic efficacy. Cancer/testis antigens are highly promising targets for immunotherapy due to their cancer-specific expression and antigenic properties, but the expression patterns of most of the more than 200 identified cancer/testis antigens in various cancers remain largely uncharacterized. In this study, we investigated the expression of the cancer/testis antigens ADAM2, CALR3 and SAGE1 in lung and breast cancer, the two most frequent human cancers, with the purpose of providing novel therapeutic targets for these diseases. We used a set of previously uncharacterized antibodies against the cancer/testis antigens ADAM2, CALR3 and SAGE1 to investigate their expression in a large panel of normal tissues as well as breast and lung cancers. Staining for the well-characterized MAGE-A proteins was included for comparison. Immunohistochemical staining confirmed previous mRNA analysis demonstrating that ADAM2, CALR3 and SAGE1 proteins are confined to testis in normal individuals. Negative tissues included plancenta, which express many other CT antigens, such as MAGE-A proteins. Surprisingly, we detected no ADAM2, CALR3 and SAGE1 in the 67 lung cancers (mainly non-small lung cancer) and 189 breast cancers, while MAGE-A proteins were present in 15% and 7–16% of these tumor types, respectively. Treatment with DNA methyltransferase inhibitors has been proposed as an attractive strategy to increase the expression of cancer/testis antigens in tumors before immunotargeting; however, neither ADAM2, CALR3 nor SAGE1 could be significantly induced in lung and breast cancer cell lines using this strategy. Our results suggest that ADAM2, CALR3 and SAGE1 cancer/testis antigens are not promising targets for immunotherapy of breast and lung cancer.

Gender-age interaction in incidence rates of childhood emotional disorders

BACKGROUND

The post-pubertal association of female gender with emotional disorder is a robust finding. However, studies exploring the association of gender and emotional disorders before puberty are few and present diverging results. The aim of this study was to present gender-specific incidence rates of emotional disorders throughout childhood.

METHOD

This is a population-based cohort study of 907,806 Danish 3- to 18-year-olds. The outcome was assignment of an emotional disorder diagnosis based on in-patient and out-patient data from The Danish Psychiatric Central Register. Outcome measures were incidence rates and cumulative incidences for unipolar depressive disorder (ICD-10: F32-F33), anxiety disorders (ICD-10: F40-F42), and emotional disorders with onset specific to childhood (ICD-10: F93).

RESULTS

Pre-pubertal incidence rates for depressive and anxiety disorders were higher for boys than girls. At age 12 years the pattern reversed. The cumulative incidence for any emotional disorder (F32-F33, F40-F42, F93) on the 11th birthday was 0.52% (95% CI 0.50-0.55) for boys and 0.31% (95% CI 0.29-0.33) for girls. On the 19th birthday cumulative incidence was 2.33% (95% CI 2.24-2.43) for boys and 3.77% (95% CI 3.64-3.90) for girls. The pre-pubertal male preponderance was also significant for depressive disorders (F32-F33, p = 0.00144) and anxiety disorders (F40-F42, F93, p < 0.00001) separately.

CONCLUSIONS

Emotional disorders seem to display a male preponderance before the age of 12 years and a female preponderance thereafter. Studies exploring this gender-age interaction are needed. Still, the results question the general assumption that females throughout the lifespan are more at risk for emotional disorders than males.

Ectopic expression of cancer/testis antigen SSX2 induces DNA damage and promotes genomic instability

SSX cancer/testis antigens are frequently expressed in melanoma tumors and represent attractive targets for immunotherapy, but their role in melanoma tumorigenesis has remained elusive. Here, we investigated the cellular effects of SSX2 expression. In A375 melanoma cells, SSX2 expression resulted in an increased DNA content and enlargement of cell nuclei, suggestive of replication aberrations. The cells further displayed signs of DNA damage and genomic instability, associated with p53-mediated G1 cell cycle arrest and a late apoptotic response. These results suggest a model wherein SSX2-mediated replication stress translates into mitotic defects and genomic instability. Arrest of cell growth and induction of DNA double-strand breaks was also observed in MCF7 breast cancer cells in response to SSX2 expression. Additionally, MCF7 cells with ectopic SSX2 expression demonstrated typical signs of senescence (i.e. an irregular and enlarged cell shape, enhanced β-galactosidase activity and DNA double-strand breaks). Since replication defects, DNA damage and senescence are interconnected and well-documented effects of oncogene expression, we tested the oncogenic potential of SSX2. Importantly, knockdown of SSX2 expression in melanoma cell lines demonstrated that SSX2 supports the growth of melanoma cells. Our results reveal two important phenotypes of ectopic SSX2 expression that may drive/support tumorigenesis: First, immediate induction of genomic instability, and second, long-term support of tumor cell growth.

Genome-wide study of association and interaction with maternal cytomegalovirus infection suggests new schizophrenia loci

Genetic and environmental components as well as their interaction contribute to the risk of schizophrenia, making it highly relevant to include environmental factors in genetic studies of schizophrenia. This study comprises genome-wide association (GWA) and follow-up analyses of all individuals born in Denmark since 1981 and diagnosed with schizophrenia as well as controls from the same birth cohort. Furthermore, we present the first genome-wide interaction survey of single nucleotide polymorphisms (SNPs) and maternal cytomegalovirus (CMV) infection. The GWA analysis included 888 cases and 882 controls, and the follow-up investigation of the top GWA results was performed in independent Danish (1396 cases and 1803 controls) and German-Dutch (1169 cases, 3714 controls) samples. The SNPs most strongly associated in the single-marker analysis of the combined Danish samples were rs4757144 in ARNTL (P=3.78 × 10(-6)) and rs8057927 in CDH13 (P=1.39 × 10(-5)). Both genes have previously been linked to schizophrenia or other psychiatric disorders. The strongest associated SNP in the combined analysis, including Danish and German-Dutch samples, was rs12922317 in RUNDC2A (P=9.04 × 10(-7)). A region-based analysis summarizing independent signals in segments of 100 kb identified a new region-based genome-wide significant locus overlapping the gene ZEB1 (P=7.0 × 10(-7)). This signal was replicated in the follow-up analysis (P=2.3 × 10(-2)). Significant interaction with maternal CMV infection was found for rs7902091 (P(SNP × CMV)=7.3 × 10(-7)) in CTNNA3, a gene not previously implicated in schizophrenia, stressing the importance of including environmental factors in genetic studies.

GAGE cancer-germline antigens are recruited to the nuclear envelope by germ cell-less (GCL)

GAGE proteins are highly similar, primate-specific molecules with unique primary structure and undefined cellular roles. They are restricted to cells of the germ line in adult healthy individuals, but are broadly expressed in a wide range of cancers. In a yeast two-hybrid screen we identified the metazoan transcriptional regulator, Germ cell-less (GCL), as an interaction partner of GAGE12I. GCL directly binds LEM-domain proteins (LAP2β, emerin, MAN1) at the nuclear envelope, and we found that GAGE proteins were recruited to the nuclear envelope inner membrane by GCL. Based on yeast two-hybrid analysis and pull-down experiments of GCL polypeptides, GCL residues 209–320 (which includes the BACK domain) were deduced sufficient for association with GAGE proteins. GAGE mRNAs and GCL mRNA were demonstrated in human testis and most types of cancers, and at the protein level GAGE members and GCL were co-expressed in cancer cell lines. Structural studies of GAGE proteins revealed no distinct secondary or tertiary structure, suggesting they are intrinsically disordered. Interestingly GAGE proteins formed stable complexes with dsDNA in vitro at physiological concentrations, and GAGE12I bound several different dsDNA fragments, suggesting sequence-nonspecific binding. Dual association of GAGE family members with GCL at the nuclear envelope inner membrane in cells, and with dsDNA in vitro, implicate GAGE proteins in chromatin regulation in germ cells and cancer cells.

Risk of schizophrenia in relation to parental origin and genome-wide divergence

BACKGROUND

Second-generation immigrants have an increased risk of schizophrenia, a finding that still lacks a satisfactory explanation. Various operational definitions of second-generation immigrants have been used, including foreign parental country of birth. However, with increasing global migration, it is not clear that parental country of birth necessarily is informative with regard to ethnicity. We compare two independently collected measures of parental foreign ethnicity, parental foreign country of birth versus genetic divergence, based on genome-wide genotypic data, to access which measure most efficiently captures the increased risk of schizophrenia among second-generation immigrants residing in Denmark.

METHOD

A case-control study covering all children born in Denmark since 1981 included 892 cases of schizophrenia and 883 matched controls. Genetic divergence was assessed using principal component analyses of the genotypic data. Independently, parental foreign country of birth was assessed using information recorded prospectively in the Danish Civil Registration System. We compared incidence rate ratios of schizophrenia associated with these two independently collected measures of parental foreign ethnicity.

RESULTS

People with foreign-born parents had a significantly increased risk of schizophrenia [relative risk (RR) 1.94 (95% confidence intervals (CI) 1.41-2.65)]. Genetically divergent persons also had a significant increased risk [RR 2.43 (95% CI 1.55-3.82)]. Mutual adjustment of parental foreign country of birth and genetic divergence showed no difference between these measures with regard to their potential impact on the results.

CONCLUSIONS

In terms of RR of schizophrenia, genetic divergence and parental foreign country of birth are interchangeable entities, and both entities have validity with regard to identifying second-generation immigrants.

Myoblasts generated by lentiviral mediated MyoD transduction of myotonic dystrophy type 1 (DM1) fibroblasts can be used for assays of therapeutic molecules

Background

Myotonic dystrophy type 1 (DM1) is the most common muscle dystrophy in adults. The disease is caused by a triplet expansion in the 3'end of the myotonic dystrophy protein kinase (DMPK) gene. In order to develop a human cell model for investigation of possible effects of antisense and RNAi effector molecules we have used lentiviral mediated myoD-forced myogenesis of DM1 patient fibroblasts.

Findings

Transduced fibroblasts show a multinuclear phenotype and express the differentiation marker myogenin. Furthermore, fluorescence in situ hybridization (FISH) analysis revealed a statistical significant increase in the amount of nuclear foci in DM1 patient fibroblasts after myogenesis. Finally, no nuclear foci were found after treatment with oligonucleotides targeting the repeat expansions.

Conclusions

The abundance of nuclear foci in DM1 patient fibroblasts increase following myogenesis, as visualized by FISH analysis. Foci were eradicated after treatment with antisense oligonucleotides. Thus, we propose that the current cell model is suitable for testing of novel treatment modalities.

Vulnerability to oxidative stress in vitro in pathophysiology of mitochondrial short-chain acyl-CoA dehydrogenase deficiency: response to antioxidants

Objective

To elucidate the pathophysiology of SCAD deficient patients who have a unique neurological phenotype, among fatty acid oxidation disorders, with early developmental delay, CNS malformations, intractable seizures, myopathy and clinical signs suggesting oxidative stress.

Methods

We studied skin fibroblast cultures from patients homozygous for ACADS common variant c.625G>A (n = 10), compound heterozygous for c.625G>A/c.319C>T (n = 3) or homozygous for pathogenic c.319C>T (n = 2) and c.1138C>T (n = 2) mutations compared to fibroblasts from patients with carnitine palmitoyltransferase 2 (CPT2) (n = 5), mitochondrial trifunctional protein (MTP)/long-chain L-3-hydroxyacyl-CoA dehydrogenase (LCHAD) (n = 7), and medium-chain acyl-CoA dehydrogenase (MCAD) deficiencies (n = 4) and normal controls (n = 9). All were exposed to 50 µM menadione at 37°C. Additonal conditions included exposure to 39°C and/or hypoglycemia. Time to 100% cell death was confirmed with trypan blue dye exclusion. Experiments were repeated with antioxidants (Vitamins C and E or N-acetylcysteine), Bezafibrate or glucose and temperature rescue.

Results

The most significant risk factor for vulnerability to menadione-induced oxidative stress was the presence of a FAO defect. SCADD fibroblasts were the most vulnerable compared to other FAO disorders and controls, and were similarly affected, independent of genotype. Cell death was exacerbated by hyperthermia and/or hypoglycemia. Hyperthermia was a more significant independent risk factor than hypoglycemia. Rescue significantly prolonged survival. Incubation with antioxidants and Bezafibrate significantly increased viability of SCADD fibroblasts.

Interpretation

Vulnerability to oxidative stress likely contributes to neurotoxicity of SCADD regardless of ACADS genotype and is significantly exacerbated by hyperthermia. We recommend rigorous temperature control in SCADD patients during acute illness. Antioxidants and Bezafibrate may also prove instrumental in their management.

Toxic response caused by a misfolding variant of the mitochondrial protein short-chain acyl-CoA dehydrogenase

BACKGROUND

Variations in the gene ACADS, encoding the mitochondrial protein short-chain acyl CoA-dehydrogenase (SCAD), have been observed in individuals with clinical symptoms. The phenotype of SCAD deficiency (SCADD) is very heterogeneous, ranging from asymptomatic to severe, without a clear genotype-phenotype correlation, which suggests a multifactorial disorder. The pathophysiological relevance of the genetic variations in the SCAD gene is therefore disputed, and has not yet been elucidated, which is an important step in the investigation of SCADD etiology.

AIM

To determine whether the disease-associated misfolding variant of SCAD protein, p.Arg107Cys, disturbs mitochondrial function.

METHODS

We have developed a cell model system, stably expressing either the SCAD wild-type protein or the misfolding SCAD variant protein, p.Arg107Cys (c.319 C > T). The model system was used for investigation of SCAD with respect to expression, degree of misfolding, and enzymatic SCAD activity. Furthermore, cell proliferation and expression of selected stress response genes were investigated as well as proteomic analysis of mitochondria-enriched extracts in order to study the consequences of p.Arg107Cys protein expression using a global approach.

CONCLUSIONS

We found that expression of the p.Arg107Cys variant SCAD protein gives rise to inactive misfolded protein species, eliciting a mild toxic response manifested though a decreased proliferation rate and oxidative stress, as shown by an increased demand for the mitochondrial antioxidant SOD2. In addition, we found markers of apoptotic activity in the p.Arg107Cys expressing cells, which points to a possible pathophysiological role of this variant protein.

Antioxidant dysfunction: potential risk for neurotoxicity in ethylmalonic aciduria

Mitochondrial dysfunction and oxidative stress are central to the molecular basis of several human diseases associated with neuromuscular disabilities. We hypothesize that mitochondrial dysfunction also contributes to the neuromuscular symptoms observed in patients with ethylmalonic aciduria and homozygosity for ACADS c.625G>A-a common variant of the short-chain acyl-coenzyme A (CoA) dehydrogenase (SCAD) enzyme in the mitochondrial fatty acid oxidation pathway. This study sought to identify the specific factors that initiate cell dysfunction in these patients. We investigated fibroblast cultures from 10 patients with neuromuscular disabilities, elevated levels of ethylmalonic acid (EMA) (>50 mmol/mol creatinine), and ACADS c.625G>A homozygosity. Functional analyses, i.e., ACADS gene and protein expression as well as SCAD enzyme activity measurements, were performed together with a global nano liquid chromatography tandem mass spectroscopy (nano-LC-MS/MS)-based screening of the mitochondrial proteome in patient fibroblasts. Moreover, cell viability of patient fibroblasts exposed to menadione-induced oxidative stress was evaluated. Loss of SCAD function was detected in the patient group, most likely due to decreased ACADS gene expression and/or elimination of misfolded SCAD protein. Analysis of the mitochondrial proteome in patient fibroblasts identified a number of differentially expressed protein candidates, including reduced expression of the antioxidant superoxide dismutase 2 (SOD2). Additionally, patient fibroblasts demonstrated significantly higher sensitivity to oxidative stress than control fibroblasts. We propose that reduced mitochondrial antioxidant capacity is a potential risk factor for ACADS c.625G>A-associated ethylmalonic aciduria and that mitochondrial dysfunction contributes to the neurotoxicity observed in patients.

Misfolding of short-chain acyl-CoA dehydrogenase leads to mitochondrial fission and oxidative stress

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare inherited disorder of the mitochondrial beta-oxidation of fatty acids. Patients with SCADD present mainly with symptoms of neuromuscular character. In order to investigate factors involved in the pathogenesis, we studied a disease-associated variant of the SCAD protein (p.Arg83Cys, c.319C>T), which is known to compromise SCAD protein folding. We investigated the consequences of overexpressing the misfolded mitochondrial protein, and thus determined whether the misfolded p.Arg83Cys SCAD proteins can elicit a toxic reaction. Human astrocytes were transiently transfected with either wild-type or p.Arg83Cys encoding cDNA, and analyzed for insoluble proteins/aggregate-formation, alterations in mitochondrial morphology, and for the presence of reactive oxygen species (ROS) in the mitochondria. The majority of cells overexpressing the p.Arg83Cys SCAD variant protein presented with an altered mitochondrial morphology of a grain-like structure, whereas the majority of the cells overexpressing wild-type SCAD presented with a normal thread-like mitochondrial reticulum. We found this grain-like structure to be associated with an increased amount of ROS. The mitochondrial morphology change was partly alleviated by addition of the mitochondrial targeted antioxidant MitoQ, indicating a ROS-induced mitochondrial fission. We therefore propose that SCAD misfolding leads to production of ROS, which in turn leads to fission and a grain-like structure of the mitochondrial reticulum. This finding indicates a toxic response elicited by misfolded p.Arg83Cys SCAD proteins.

Psychiatric family history and schizophrenia risk in Denmark: which mental disorders are relevant?

BACKGROUND

A family history of schizophrenia is the strongest single indicator of individual schizophrenia risk. Bipolar affective disorder and schizo-affective disorders have been documented to occur more frequently in parents and siblings of schizophrenia patients, but the familial occurrence of the broader range of mental illnesses and their role as confounders have not been studied in large population-based samples.

METHOD

All people born in Denmark between 1955 and 1991 (1.74 million) were followed for the development of schizophrenia (9324 cases) during 28 million person-years at risk. Information of schizophrenia in cohort members and psychiatric history in parents and siblings was established through linkage with the Danish Psychiatric Central Register. Data were analysed using log-linear Poisson regression.

RESULTS

Schizophrenia was, as expected, strongly associated with schizophrenia and related disorders among first-degree relatives. However, almost any other psychiatric disorder among first-degree relatives increased the individual's risk of schizophrenia. The population attributable risk associated with psychiatric family history in general was 27.1% whereas family histories including schizophrenia only accounted for 6.0%. The general psychiatric family history was a confounder of the association between schizophrenia and urbanization of place of birth.

CONCLUSIONS

Clinically diagnosed schizophrenia is associated with a much broader range of mental disorders in first-degree relatives than previously reported. This may suggest risk haplotypes shared across many disorders and/or shared environmental factors clustering in families. Failure to take the broad range of psychiatric family history into account may bias results of all risk-factor studies of schizophrenia.

Mitochondrial proteomics on human fibroblasts for identification of metabolic imbalance and cellular stress

Background

Mitochondrial proteins are central to various metabolic activities and are key regulators of apoptosis. Disturbance of mitochondrial proteins is therefore often associated with disease. Large scale protein data are required to capture the mitochondrial protein levels and mass spectrometry based proteomics is suitable for generating such data. To study the relative quantities of mitochondrial proteins in cells from cultivated human skin fibroblasts we applied a proteomic method based on nanoLC-MS/MS analysis of iTRAQ-labeled peptides.

Results

When fibroblast cultures were exposed to mild metabolic stress – by cultivation in galactose medium- the amount of mitochondria appeared to be maintained whereas the levels of individual proteins were altered. Proteins of respiratory chain complex I and IV were increased together with NAD⁺-dependent isocitrate dehydrogenase of the citric acid cycle illustrating cellular strategies to cope with altered energy metabolism. Furthermore, quantitative protein data, with a median standard error below 6%, were obtained for the following mitochondrial pathways: fatty acid oxidation, citric acid cycle, respiratory chain, antioxidant systems, amino acid metabolism, mitochondrial translation, protein quality control, mitochondrial morphology and apoptosis.

Conclusion

The robust analytical platform in combination with a well-defined compendium of mitochondrial proteins allowed quantification of single proteins as well as mapping of entire pathways. This enabled characterization of the interplay between metabolism and stress response in human cells exposed to mild stress.

Mitochondrial fatty acid oxidation defects--remaining challenges

Mitochondrial fatty acid oxidation defects have been recognized since the early 1970s. The discovery rate has been rather constant, with 3-4 'new' disorders identified every decade and with the most recent example, ACAD9 deficiency, reported in 2007. In this presentation we will focus on three of the 'old' defects: medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, riboflavin responsive multiple acyl-CoA dehydrogenation (RR-MAD) deficiency, and short-chain acyl-CoA dehydrogenase (SCAD) deficiency. These disorders have been discussed in many publications and at countless conference presentations, and many questions relating to them have been answered. However, continuing clinical and pathophysiological research has raised many further questions, and new ideas and methodologies may be required to answer these. We will discuss these challenges. For MCAD deficiency the key question is why 80% of symptomatic patients are homozygous for the prevalent ACADM gene variation c.985A > G whereas this is found in only approximately 50% of newborns with a positive screen. For RR-MAD deficiency, the challenge is to find the connection between variations in the ETFDH gene and the observed deficiency of a number of different mitochondrial dehydrogenases as well as deficiency of FAD and coenzyme Q(10). With SCAD deficiency, the challenge is to elucidate whether ACADS gene variations are disease-associated, especially when combined with other genetic/cellular/environmental factors, which may act synergistically.

The ACADS gene variation spectrum in 114 patients with short-chain acyl-CoA dehydrogenase (SCAD) deficiency is dominated by missense variations leading to protein misfolding at the cellular level

Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is an inherited disorder of mitochondrial fatty acid oxidation associated with variations in the ACADS gene and variable clinical symptoms. In addition to rare ACADS inactivating variations, two common variations, c.511C > T (p.Arg171Trp) and c.625G > A (p.Gly209Ser), have been identified in patients, but these are also present in up to 14% of normal populations leading to questions of their clinical relevance. The common variant alleles encode proteins with nearly normal enzymatic activity at physiological conditions in vitro. SCAD enzyme function, however, is impaired at increased temperature and the tendency to misfold increases under conditions of cellular stress. The present study examines misfolding of variant SCAD proteins identified in patients with SCAD deficiency. Analysis of the ACADS gene in 114 patients revealed 29 variations, 26 missense, one start codon, and two stop codon variations. In vitro import studies of variant SCAD proteins in isolated mitochondria from SCAD deficient (SCAD-/-) mice demonstrated an increased tendency of the abnormal proteins to misfold and aggregate compared to the wild-type, a phenomenon that often leads to gain-of-function cellular phenotypes. However, no correlation was found between the clinical phenotype and the degree of SCAD dysfunction. We propose that SCAD deficiency should be considered as a disorder of protein folding that can lead to clinical disease in combination with other genetic and environmental factors.

Handling of human short-chain acyl-CoA dehydrogenase (SCAD) variant proteins in transgenic mice

To investigate the in vivo handling of human short-chain acyl-CoA dehydrogenase (SCAD) variant proteins, three transgenic mouse lines were produced by pronuclear injection of cDNA encoding the wild-type, hSCAD-wt, and two disease causing folding variants hSCAD-319C>T and hSCAD-625G>A. The transgenic mice were mated with an SCAD-deficient mouse strain (BALB/cByJ) and, in the second generation, three mouse lines were obtained without endogenous SCAD expression but harboring hSCAD-wt, hSCAD-319C>T, and hSCAD-625G>A transgenes, respectively. All three lines had expression of the transgene at the RNA level in liver, muscle or brain tissues. Expression at the protein level was detected only in the brain tissue of hSCAD-wt mice, but here it was significantly higher than the level of endogenous SCAD protein in control mouse brains--in correlation with expression at the RNA level. The results may indicate that the two hSCAD folding variants are degraded by the mouse mitochondrial protein quality control system. Indeed, pulse-chase studies with isolated mitochondria revealed that soluble variant hSCAD protein was rapidly eliminated. This is in agreement with the fact that no disease phenotype developed for any of the lines transgenic for the hSCAD folding variants. The indicated remarkable efficiency of the mouse protein quality control system in the degradation of SCAD folding variants should be further substantiated and investigated, since it might indicate ways to prevent disease-causing effects.

Variations in IBD (ACAD8) in children with elevated C4-carnitine detected by tandem mass spectrometry newborn screening

The isobutyryl-CoA dehydrogenase (IBD) enzyme is involved in the degradation of valine. IBD deficiency was first reported in 1998 and subsequent genetic investigations identified acyl-CoA dehydrogenase (ACAD) 8, now IBD, as the gene responsible for IBD deficiency. Only three individuals homozygous or compound heterozygous for variations in the IBD gene have been reported. We present IBD deficiency in an additional four newborns with elevated C(4)-carnitine identified by tandem mass spectrometry (MS/MS) screening in Denmark and the United States. Three showed urinary excretions of isobutyryl-glycine, and in vitro probe analysis of fibroblasts from two newborns indicated enzymatic IBD defect. Molecular genetic analysis revealed seven new rare variations in the IBD gene (c.348C>A, c.400G>T, c.409G>A, c.455T>C, c.958G>A, c.1000C>T and c.1154G>A). Furthermore, sequence analysis of the short-chain acyl-CoA dehydrogenase (SCAD) gene revealed heterozygosity for the prevalent c.625G>A susceptibility variation in all newborns and in the first reported IBD patient. Functional studies in isolated mitochondria demonstrated that the IBD variations present in the Danish newborn (c.409G>A and c.958G>A) together with a previously published IBD variation (c.905G>A) disturbed protein folding and reduced the levels of correctly folded IBD tetramers. Accordingly, low/no IBD residual enzyme activity was detectable when the variant IBD proteins were overexpressed in Chang cells.

Sibship characteristics during upbringing and schizophrenia risk

The potential association between sibship characteristics and the risk of schizophrenia has been investigated previously. However, methods have differed and results have been conflicting. The authors explored the association between birth order, sibship size, and birth interval to siblings and schizophrenia while accounting for potential confounders. Using Danish Civil Registration System data, the authors established a cohort of 763,000 people. Schizophrenia was identified by linkage with the Danish Psychiatric Central Register. Overall, 2,536 people developed schizophrenia from 1986 to 2001. Children with no siblings and children with three or more siblings had significantly increased risks (relative risk = 1.22 and 1.27, respectively). This association was explained by change of residence and urbanization during upbringing. Children with half siblings had a significantly increased risk (relative risk = 1.20). The authors found a significantly increased risk associated with siblings 7-8 and 11-14 years younger (relative risk = 1.30 and 1.22, respectively) combined with a significantly decreased risk associated with siblings 2-10 and 12 or more years older (relative risk = 0.92 and 0.82, respectively). There was no consistent pattern between the birth interval to siblings and schizophrenia risk. Results of the association between sibship characteristics and schizophrenia from a single country may not be comparable with results from other countries, and sibship characteristics are minor determinants of schizophrenia risk.

The incidence and prevalence of pervasive developmental disorders: a Danish population-based study

BACKGROUND

Based on prevalence studies and the few incidence studies of pervasive developmental disorders (PDDs) the prevalence and incidence of these disorders have been claimed to be increasing.

METHOD

The annual and age-specific prevalence and incidence rates of childhood autism, atypical autism, Asperger's disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS) in Denmark during the period 1971--2000 in children younger than 10 years were estimated using data from the Danish Psychiatric Central Register.

RESULTS

A total of 2.4 million children younger than 10 years were followed and 2061 cases with the PDDs studied were identified. Generally, the prevalence and incidence rates of the PDDs studied were stable until the early 1990s after which an increase in the occurrence of all disorders was seen, until 2000. The annual incidence rate per 10000 children younger than 10 years was 2.0 for childhood autism, 0.7 for atypical autism, 1.4 for Asperger's disorder, and 3.0 for PDD-NOS in 2000. We calculated a 'corrected' prevalence of childhood autism at 11.8, atypical autism at 3.3, Asperger's disorder at 4.7, and PDD-NOS at 14.6 per 10,000 children younger than 10 years on 1 January 2001.

CONCLUSIONS

We found that the estimated prevalences of the PDDs studied were probably underestimated. Furthermore, the increasing prevalence and incidence rates during the 1990s may well be explained by changes in the registration procedures and more awareness of the disorders, although a true increase in the incidence cannot be ruled out.

Individual and familial risk factors for bipolar affective disorders in Denmark

BACKGROUND

Few population-based studies have addressed risk factors for bipolar affective disorder.

OBJECTIVE

To study the possible association between bipolar affective disorder and history of mental illness in a parent or sibling; urbanicity of birth place; season of birth; sibship characteristics, including birth order; influenza epidemics during pregnancy; and early parental loss.

DESIGN

We used a population-based cohort of 2.1 million individuals based on data from the Danish Civil Registration System linked with the Danish Psychiatric Central Register.

SETTING

Nationwide population-based sample of all individuals hospitalized or in outpatient clinic contact for the first time with bipolar affective disorder. Patients Overall, 2299 individuals were first diagnosed with bipolar affective disorder during the 31.8 million person-years of follow-up.

RESULTS

Risk of bipolar affective disorder was associated with a history of bipolar affective disorder as well as other psychiatric disorders, including schizophrenia and schizoaffective disorder, in parents or siblings. People with a first-degree relative with bipolar affective disorder had a 13.63-fold (95% confidence interval, 11.81-15.71) increased risk of bipolar affective disorder. No other consistent associations were found with the exception of an association between early parental loss, in particular maternal, and bipolar affective disorder. Children who experienced maternal loss before their fifth birthday had a 4.05 (95% confidence interval, 1.68-9.77) increased risk of bipolar affective disorder.

CONCLUSIONS

Early parental loss may represent both environmental and genetic risk factors for bipolar affective disorder. Most of the risk factors included in our study that previously have been associated with schizophrenia were not associated with bipolar affective disorder, supporting that the 2 disorders may be at least partially separate etiological entities.

ICP is lower during propofol anaesthesia compared to isoflurane and sevoflurane

OBJECTIVES

Propofol is a cerebral vasoconstrictor while inhalation anaesthetics like isoflurane and sevoflurane act as cerebral vasodilators in both animal and human studies. This difference of action upon cerebral vessels might implicate a lower ICP during propofol anaesthesia. Cerebral metabolism is decreased by all three anaesthetics. In a prospective, randomised multicenter study ICP was compared during anaesthesia with propofol, isoflurane and sevoflurane.

METHODS

117 patients subjected to elective craniotomy for supratentorial tumour. Propofol: N = 41; isoflurane: N = 38; sevoflurane: N = 38. Nitrous oxide was omitted and all anaesthetics were supplemented with a continuous infusion of fentanyl. ICP was measured subdurally after removal of the bone flap. MABP, CPP, PCO2, AVDO2, rectal temperature, tumour size and midline shift were registered too.

STATISTICS

Kruskal-Wallis Variance on Ranks. All values in medians with range. P < 0.05 was considered significant.

RESULTS

ICP (mmHg): propofol 7 (-1-20), isoflurane 12 (1-29), sevoflurane 11 (2-32). ICP was significantly lower in the propofol group compared to the isofluane and sevoflurane groups. CPP (mmHg): propofol 80 (45-104), isoflurane 60 (32-84), sevoflurane 63 (44-77). CPP was significantly higher in the propofol group compared to the isoflurane and sevoflurane groups. AVDO2 (mmol/l): propofol 3.1 (0.9-5.1), isoflurane 2.5 (1.1-4.5), sevoflurane 2.6 (0.8-4.1). AVDO2 was significantly higher in the propofol group compared to the isoflurane and sevoflurane groups. No significant differences in PCO2, rectal temperature, tumour size and midline shift were found.

CONCLUSIONS

Subdural ICP is significantly lower during propofol anaesthesia compared to isoflurane and sevoflurane anaesthesia. CPP and AVDO2 are significantly higher during propofol anaesthesia compared to isoflurane and sevoflurane anaesthesia.

Recurrent vomiting and ethylmalonic aciduria associated with rare mutations of the short-chain acyl-CoA dehydrogenase gene

We report identification of short-chain acyl-CoA dehydrogenase (SCAD) deficiency in a 12-year-old boy who suffered from recurrent attacks of vomiting once or twice a year from infancy. Growth and development were normal and there were no muscular symptoms. Metabolic screening was performed during a hospitalization at 8 years of age and revealed an increased excretion of ethylmalonic acid (EMA; 45-80 mmol/mol creatinine, normal 0.2-6.6), suggesting a degradation defect of short-chain fatty acids. An increased n-butyrylcarnitine was found in freshly collected serum (0.9 micromol/L; normal <0.4) but not in dry blood spots. Neither of the frequent SCAD gene variants 625G>A and 511C>T was present, but direct sequencing of the promoter and coding regions of the SCAD gene revealed that the patient had mutations on both alleles: 417G>C (Trpl15Cys) and 1095G>T (Gln341His). Neither mutation has been described before in compound heterozygosity or homozygosity. Enzymatic investigations subsequently confirmed a defect of SCAD in both fibroblasts and muscle extracts. Furthermore, expression studies of both mutations demonstrated impaired enzyme function or structure. To our knowledge, this case is the first description of a patient with proven SCAD deficiency presenting with recurrent emesis but without other symptoms, and emphasizes the wide clinical phenotype of this disorder.

Evidence of a dose-response relationship between urbanicity during upbringing and schizophrenia risk

BACKGROUND

Many studies have demonstrated that an urban birth or upbringing increases schizophrenia risk, but no studies have been able to distinguish between these effects. The objectives of this study were to discriminate the effect of urbanicity at birth from an effect of urbanicity during upbringing, and to identify particularly vulnerable age periods and a possible dose-response relationship between urbanicity during upbringing and schizophrenia risk.

METHODS

Using data from the Danish Civil Registration System, we established a population-based cohort of 1.89 million people, which included information on place of birth, place of residence during upbringing, and the accumulated number of years lived in each category of the 5-level degree of urbanization during upbringing. Schizophrenia in cohort members and mental illness in a parent or sibling were identified by linkage with the Danish Psychiatric Central Register.

RESULTS

Individuals living in a higher degree of urbanization than 5 years earlier had a 1.40-fold (95% confidence interval, 1.28-1.51) increased risk, while individuals living in a lower degree of urbanization than 5 years earlier had a 0.82-fold (95% confidence interval, 0.77-0.88) decreased risk of schizophrenia. For fixed urbanicity at the 15th birthday, risk increased with increasing degree of urbanization at birth. Furthermore, the more years lived in the higher the degree of urbanization, the greater the risk. Individuals who lived their first 15 years in the highest category of the 5-level urbanicity had a 2.75-fold (95% confidence interval, 2.31-3.28) increased risk of schizophrenia.

CONCLUSION

Continuous, or repeated, exposures during upbringing that occur more frequently in urbanized areas may be responsible for the association between urbanization and schizophrenia risk.

[Sibships characteristics, influenza and risk of schizophrenia. A population-based cohort study]

INTRODUCTION

To address the hypothesis that infections, perhaps prenatal exposure to influenza virus, might increase the risk of schizophrenia we studied the possible association between schizophrenia risk and birth order, sibship size, interval between siblings, and influenza prevalence.

MATERIAL AND METHODS

We established a population-based cohort of 1,746,366 persons born to Danish woman who themselves were born since 1935 using data from the Civil Registration System. Schizophrenia in cohort members (n = 2669) and their parents was identified by linkage with the Danish Psychiatric Case Register. Influenza notifications per month in Denmark were obtained from the National Board of Health and Statens Serum Institut.

RESULTS

We found no association between birth order and schizophrenia risk or between schizophrenia risk and influenza prevalence during any month of prenatal life. Coming from a large sibship and having a short interval to the nearest older or younger sibling was associated with an increased risk of schizophrenia.

DISCUSSION

Our findings do not add support to the hypothesis that schizophrenia is associated with prenatal exposure to influenza virus or other common infections, but are compatible with the hypothesis that environmental exposure, perhaps to common infections in childhood, may be a risk factor.

Family history, place and season of birth as risk factors for schizophrenia in Denmark: a replication and reanalysis

BACKGROUND

Although a family history of schizophrenia is the strongest individual risk factor for schizophrenia, environmental factors related to urbanicity may contribute to a substantial proportion of the population occurrence of the disease.

AIMS

This study replicates previous findings in four mutually exclusive Danish study populations, including out-patient information, ICD-10 diagnoses of schizophrenia, and a broader adjustment for mental illness in family members.

METHOD

We established a population-based cohort of 2.66 million Danish people using data from the Civil Registration System linked with the Psychiatric Case Register.

RESULTS

Overall, 10 264 persons developed schizophrenia during the 50.7 million person-years of follow-up. The risk of schizophrenia was increased by urbanicity of place of birth and by family history of schizophrenia or other mental disorders.

CONCLUSIONS

Urban-rural differences of schizophrenia risk were replicated and could not be associated with the potential sources of bias we assessed. Environmental factors underlying the effect of place of birth are major determinants of schizophrenia occurrence at the population level, although the effect of family history is the strongest at the individual level.

[The Cusum score. A tool for evaluation of clinical competence]

INTRODUCTION

The cusum analysis (cummulative summation) is a statistical technique used to assess the competence of medical trainees. We wanted to re-examine the validity of the test as a technique for qualitative assessment of competence, as well as a technique for monitoring the level of specialists' competence.

METHODS

Doctors in two anaesthetic departments were asked to plot the cusum as they performed the following procedures: epidural and spinal analgesia, insertion of central venous and arterial cannulae.

RESULTS

Data were collected over a year. Thirty-five doctors were asked to plot the cusum. The plots were returned by 75% (9/12) of the first year trainees, 50% (4/8) of the second- and third-year trainees, and 20% (1/5) of the four- and five-year trainees. From the specialists and consultants on the staff, we received 66% (4/6) and 50% (2/4). The correlation, according to the level of competence respecting spinal and epidural techniques, is shown in Figures 1 and 2.

DISCUSSION

We found, that the cusum analysis is a valid and practical technique for the qualitative assessment of clinical competence as well as a tool for monitoring continuous professional development. The technique can be used in a number of settings. With the increasing demand in health care for continuous quality assurance, the analysis can be used both in personal professional monitoring and in monitoring of performance during training.

Cancer risk in a cohort of polio patients

Poliomyelitis has hypothetically been associated with an increased risk of central nervous system (CNS) tumors. The present study was performed to examine not only the risk of CNS tumors but also the overall risk of cancer among a cohort of 5,883 polio patients. Patients diagnosed with acute poliomyelitis in the Danish capital, Copenhagen, between 1919 and 1954 were identified and followed with respect to cancer. Information on vital status and cancer diagnoses was obtained through linkage with the Danish Civil Registration System and the Danish Cancer Registry, respectively. The ratio of observed number of cancers to the number expected from population-based incidence rates, i.e., the standardized incidence ratio (SIR), served as measure of the relative cancer risk. Overall, 717 cases of cancer were observed among 5,883 polio patients during 249,084 person-years of follow-up vs. an expected number of 645 (SIR = 1.11 [95% confidence interval 1.03 to 1.20])). The increased risk was restricted to female polio patients (SIR = 1.18 [1.07 to 1.30]), among whom the risk was particularly high for breast cancer (SIR = 1.35 [1.12 to 1.61]) and for skin cancer (SIR = 1.66 [1.32 to 2.07]). The risk of breast cancer was highest among women with a history of paralytic polio (SIR = 1.62 [1.24 to 2.10]). The observed number of CNS tumors did not exceed the expected (SIR = 1.09 [0.72 to 1.60]). Women diagnosed with poliomyelitis, in particular paralytic polio, may be at increased risk of breast cancer. There was no association between malignancies of the CNS and poliomyelitis.