[An attempt to identify 22q11.2 microdeletions in samples of the Hungarian schizophrenia DNA bank by multiplex ligation-based probe amplification (MLPA): literature review, methodology and results]. / 22q11.2 deléciók azonosítási kísérlete magyar szkizofrénia biobank mintákon multiplex ligációs alapú próba amplifikáció (MLPA) módszerrel: irodalmi összefoglalás, módszertani leírás és eredmények.

Schizophrenia is a severe debilitating psychiatric disorder, with a typical onset in adolescence or early adulthood. This condition is characterized by heterogeneous symptoms (hallucinations, delusions, disorganized behaviour, affective flattening, and social isolation) and a life-time prevalence of 0.5-1.2%. In spite of the efforts to uncover the etiology of the disorder, its pathogenesis and neurobiological background are poorly understood. Given the high heritability in schizophrenia, genetic research remains an important area of focus. Besides the common variations of low penetrance - single nucleotid polymorphisms (SNPs) -, rare variants, mainly copy number variations (CNVs) play a role in the genetic architecture of the disorder. The most frequent CNV associated with schizophrenia is the hemizygous deletion of the 22q11.2 region. According to previous research this genetic variant occurs in 1% of the patients and conversely, 25% of the carriers of the 22q11.2 microdeletion will develop schizophrenia. The 22q11.2 deletion syndrome (22Q11DS, velocardiofacial (VCFS) syndrome, DiGeorge-syndrome) is usually a childhood diagnosis. Its prevalence is 1:2000-4000 considering all births. Patients can demonstrate heart developmental disorders, craniofacial (elongated face, hypertelorism), immunological (thymus-hypoplasia), endocrinological (hypocalcaemia) abnormalities, and neurodevelopmental alterations, but only a proportion will have these abnormalities due to incomplete penetrance. The variable symptoms complicate the recognition of the syndrome in the day to day medical practice. 25% of the known 22Q11DS patients develop schizophrenia but the risk of neuropsychiatric problems, like autism, ADHD and childhood conduct disorder is also increased, while early onset Parkinson's disease in also more frequent in adults. The schizophrenia phenotype is not distinguishable at the moment in patients with or without the 22q11 deletion. But emerging evidence suggests that early onset Parkinson's disease is more frequent in 22Q11DS and the effects of clozapine treatment could be different in schizophrenia with 22Q11DS. The question arises what is the incidence rate of the 22q11.2 microdeletion among our Hungarian DNA samples with schizophrenia. To answer the question, we utilized a new method used in routine genetic diagnostics, multiplex ligation-based probe amplification (MLPA). Although we genotyped the DNA of 315 Hungarian schizophrenia patients, we found no 22Q11DS in this cohort. The findings are discussed in terms of basic research and their translation into everyday clinical practice.

[Investigation of CNTF, COMT, DDR1, DISC1, DRD2, DRD3, and DTNBP1 candidate genes in schizophrenia: Results from the Hungarian SCHIZOBANK Consortium]. / CNTF, COMT, DDR1, DISC1, DRD2, DRD3 és DTNBP1 kandidáns gének vizsgálata szkizofréniában: eredmények a Magyar SCHIZOBANK Konzorcium vizsgálatából.

Schizophrenia is a chronic, debilitating psychiatric disorder characterized by heterogeneous clinical symptoms. Although the pathogenesis of this disorder is poorly understood, several lines of evidence support the role of both common and rare genetic variants in the etiology of schizophrenia. Common variants, single nucleotide polymorphisms can be investigated by candidate gene association studies or genome-wide association studies, while rare variants, single nucleotide variants are assessable by means of candidate gene resequencing or whole-exome and genome sequencing using next generation sequencing. In this study we investigated polymorphisms of 7 candidate genes in a Hungarian schizophrenia cohort. Candidate genes were chosen on the basis of previous results and biological plausibility. 390 patients were recruited in 5 centers in the framework of the Hungarian SCHIZOBANK Consortium, the schizophrenia sample was contrasted to 1069 healthy control individuals. In this sample SNPs of DDR1 and DRD2 genes demonstrated significant association with schizophrenia. The role of DDR1 and DRD2 genes in the etiology of schizophrenia warrant further investigation, based on their genomic localization and biological functions.

Theory of mind impairments in patients with deficit schizophrenia.

The deficit syndrome, a subgroup within schizophrenia, is characterized by enduring, idiopathic negative symptoms. Theory of mind (ToM), a domain of social cognition, is the ability of attributing mental states to ourselves and other people. ToM impairments have not been investigated earlier in deficit schizophrenia. The aim of the present study was to examine ToM differences between patients with deficit (SZ-D) and non-deficit schizophrenia (SZ-ND). Gender differences were also investigated, and based on the literature a better ToM performance was expected in female patients. The participants were 28 patients with SZ-ND, 30 patients with SZ-D, and 29 healthy control volunteers. The "Reading the Mind in the Eyes Test" was used to asses ToM deficits. Control subjects outperformed both patient groups, while there were no significant differences between the two schizophrenia subgroups. In female subjects, both controls and patients with SZ-ND performed significantly better than the SZ-D subgroup. In male subjects, controls performed significantly better than both patient groups. The "diminished emotional range" and the "curbing of interest" items of the Schedule for the Deficit Syndrome showed significant negative relationship with the ToM score. Our main finding is that female subjects with SZ-ND performed significantly better than female subjects with SZ-D.

Glycogen synthase kinase 3 beta gene structural variants as possible risk factors of bipolar depression.

The glycogen synthase kinase 3B (GSK3B) is an important target protein of several antidepressants, such as lithium, a mood stabilizer. Recent studies associated structural variations of the GSK3B gene to bipolar disorder (BP), although replications were not conclusive. Here we present data on copy number variations (CNVs) of the GSK3B gene probing the 9th exon region in 846 individuals (414 controls, 172 patients with major depressive disorder (MDD) and 260 with BP). A significant accumulation (odds ratio: 5.5, P = 0.00051) of the amplified exon 9 region was found in patients (22 out of 432) compared to controls (4 of 414). Analyzing patient subgroups, GSK3B structural variants were found to be risk factors of BP particularly (P = 0.00001) with an odds ratio of 8.1 while no such effect was shown in the MDD group. The highest odds (19.7 ratio) for bipolar disorder was observed in females with the amplified exon 9 region. A more detailed analysis of the identified GSK3B CNV by a set of probes covering the GSK3B gene and the adjacent NR1I2 and C3orf15 genes showed that the amplified sequences contained 3' (downstream) segments of the GSK3B and NR1I2 genes but none of them involved the C3orf15 gene. Therefore, the copy number variation of the GSK3B gene could be described as a complex set of structural variants involving partial duplications and deletions, simultaneously. In summary, here we confirmed significant association of the GSK3B CNV and bipolar disorder pointing out that the copy number and extension of the CNV varies among individuals.

[SCHIZOBANK - The Hungarian national schizophrenia biobank and its role in schizophrenia research and in personalized medicine]. / Magyar szkizofrénia-biobank a szkizofréniakutatás és a személyre szabott orvoslás szolgálatában.

Delineating the pathogenesis of multifactorial diseases is a major challenge of the postgenomial era. Genetic factors are known to play an important role in the pathogenesis of certain psychiatric disorders as well as in the development of adverse reactions to psychoactive drugs. Containing large numbers of samples and linking them clinical data, biobanks are gaining importance in the studies of chronic multifactorial diseases. Several biobanks are under establishment in Hungary. The first initiative to collect samples in neurological and psychiatric disorders was the NEPSYBANK coordinated by the Hungarian Society of Clinical Neurogenetics. The national biobank network is currently established by the NEKIFUT project of the National Office of Research and Technology. In this article we describe the structure, logistics and informatical background of the national schizophrenia biobank (SCHIZOBANK). The initiative of the SCHIZOBANK originates from a consortium in which academy and health industry partners are collecting biological materials and data in five major psychiatric center under the coordination of the Medical and Health Science Center of the University of Debrecen. We review other international schizophrenia biobanks as well. Major strength of the SCHIZOBANK is the collection of very detailed phenotypic data and of RNA and plasma both in psychotic and non-psychotic state of the patient which permits longitudinal follow-up and the study of both static and dynamically changing transcriptomic, proteomic and metabolomic markers. The collection of the SCHIZOBANK is available not only to consortial partners but to other national and international research groups as well.

Genes and environments in schizophrenia: The different pieces of a manifold puzzle.

Genetic research targeting schizophrenia has undergone tremendous development during recent years. Supported by recently developed high-throughput genotyping technologies, both rare and common genetic variants have been identified that show consistent association with schizophrenia. These results have been replicated by independent studies and refined in meta-analyses. The genetic variation uncovered consists of common alleles, i.e. single nucleotide polymorphisms (SNPs) conveying small effects (odds ratios below 1.1) on disease risk. The source of rare variants is copy number variations (CNVs), only detectable in a small proportion of patients (3-5% for all known CNVs) with schizophrenia, furthermore extremely rare de novo mutations captured by next generation sequencing, the most recent technological advancement in the field. Despite these findings, the search for the genetic architecture underlying schizophrenia continues since these variants explain only a small proportion of the overall phenotypic variance. Gene-environment interactions provide a compelling model for resolving this paradox and interpreting the risk factors of schizophrenia. Epidemiologically proven risk factors, such as prenatal infection, obstetric complications, urbanicity, cannabis, and trauma have been demonstrated to interact with genetic risk, giving rise to higher prevalence rates or more severe symptomatology in individuals with direct or indirect genetic predisposition for schizophrenia. Further research will have to explain how the different forms of genetic variation interact and how environmental factors modulate their effects. Moreover, the challenging question lying ahead of us is how genetic and environmental factors translate to molecular disease pathways. New approaches, including animal studies and in vitro disease modeling, as well as innovative real-world environment assessment methods, will help to understand the complex etiology of schizophrenia.