An integrative approach to investigate the respective roles of single-nucleotide variants and copy-number variants in Attention-Deficit/Hyperactivity Disorder.

Many studies have attempted to investigate the genetic susceptibility of Attention-Deficit/Hyperactivity Disorder (ADHD), but without much success. The present study aimed to analyze both single-nucleotide and copy-number variants contributing to the genetic architecture of ADHD. We generated exome data from 30 Brazilian trios with sporadic ADHD. We also analyzed a Brazilian sample of 503 children/adolescent controls from a High Risk Cohort Study for the Development of Childhood Psychiatric Disorders, and also previously published results of five CNV studies and one GWAS meta-analysis of ADHD involving children/adolescents. The results from the Brazilian trios showed that cases with de novo SNVs tend not to have de novo CNVs and vice-versa. Although the sample size is small, we could also see that various comorbidities are more frequent in cases with only inherited variants. Moreover, using only genes expressed in brain, we constructed two "in silico" protein-protein interaction networks, one with genes from any analysis, and other with genes with hits in two analyses. Topological and functional analyses of genes in this network uncovered genes related to synapse, cell adhesion, glutamatergic and serotoninergic pathways, both confirming findings of previous studies and capturing new genes and genetic variants in these pathways.

Comparison of two methods of RNA extraction from formalin-fixed paraffin-embedded tissue specimens.

The present study aimed to compare two different methods of extracting RNA from formalin-fixed paraffin-embedded (FFPE) specimens of diffuse large B-cell lymphoma (DLBCL). We further aimed to identify possible influences of variables--such as tissue size, duration of paraffin block storage, fixative type, primers used for cDNA synthesis, and endogenous genes tested--on the success of amplification from the samples. Both tested protocols used the same commercial kit for RNA extraction (the RecoverAll Total Nucleic Acid Isolation Optimized for FFPE Samples from Ambion). However, the second protocol included an additional step of washing with saline buffer just after sample rehydration. Following each protocol, we compared the RNA amount and purity and the amplification success as evaluated by standard PCR and real-time PCR. The results revealed that the extra washing step added to the RNA extraction process resulted in significantly improved RNA quantity and quality and improved success of amplification from paraffin-embedded specimens.

Pathophysiology and molecular aspects of diffuse large B-cell lymphoma.

Diffuse large B-Cell lymphoma is the most common subtype of non-Hodgkin lymphoma in the West. In Brazil, it is the fifth cause of cancer, with more than 55,000 cases and 26,000 deaths per year. At Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - HCFMUSP, diffuse large B-Cell lymphoma represents 49.7% of all non-Hodgkin lymphoma cases. Initially, the classification of non-Hodgkin lymphoma was based on morphology, but advances in immunology and molecular medicine allowed the introduction of a biological classification for these diseases. As for other cancers, non-Hodgkin lymphoma involves patterns of multifactorial pathogenesis with environmental factors, as well as genetic, occupational and dietary factors, contributing to its development. Multiple lesions involving molecular pathways of B-cell proliferation and differentiation may result in the activation of oncogenes such as the BCL2, BCL6, and MYC genes and the inactivation of tumor suppressor genes such as p53 and INK4, as well as other important transcription factors such as OCT-1 and OCT-2. A dramatic improvement in survival was seen after the recent introduction of the anti-CD20 monoclonal antibody. The association of this antibody to the cyclophosphamide, hydroxydaunorubicin, oncovin and prednisolone (CHOP) regimen has increased overall survival of diffuse large B-Cell lymphoma and follicular lymphoma patients by 20%. However, 50% of all diffuse large B-Cell lymphoma patients remain incurable, creating a demand for more research with new advances in treatment. Thus, it is important to know and understand the key factors and molecular pathways involved in the pathogenesis of diffuse large B-Cell lymphoma.

Pathophysiology and molecular aspects of diffuse large B-cell lymphoma

Diffuse large B-Cell lymphoma is the most common subtype of non-Hodgkin lymphoma in the West. In Brazil, it is the fifth cause of cancer, with more than 55,000 cases and 26,000 deaths per year. At Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - HCFMUSP, diffuse large B-Cell lymphoma represents 49.7% of all non-Hodgkin lymphoma cases. Initially, the classification of non-Hodgkin lymphoma was based on morphology, but advances in immunology and molecular medicine allowed the introduction of a biological classification for these diseases. As for other cancers, non-Hodgkin lymphoma involves patterns of multi factorial pathogenesis with environmental factors, as well as genetic, occupational and dietary factors, contributing to its development. Multiple lesions involving molecular pathways of B-cell proliferation and differentiation may result in the activation of oncogenes such as the BCL2, BCL6,and MYC genes and the inactivation of tumor suppressor genes such as p53 and INK4, as well as other important transcription factors such as OCT-1 and OCT-2. A dramatic improvement in survival was seen after the recent introduction of the anti-CD20 monoclonal antibody. The association of this antibody to the cyclophosphamide, hydroxydaunorubicin, oncovin and prednisolone (CHOP) regimen has increased overall survival of diffuse large B-Cell lymphoma and follicular lymphoma patients by 20%. However, 50% of all diffuse large B-Cell lymphoma patients remain incurable, creating a demand for more research with new advances in treatment. Thus, it is important to know and understand the key factors and molecular pathways involved in the pathogenesis of diffuse large B-Cell lymphoma.

Comparação de três protocolos distintos para extração de RNA de amostras fixadas em formalina e emblocadas em parafina / Comparison of three different protocols for extracting RNA from formalin-fixed paraffin-embedded tissues

INTRODUÇÃO: Tecidos fixados em formalina e emblocados em parafina (FFEP) são importantes fontes de amostras para estudos retrospectivos. Apesar de sua capacidade de preservação de proteínas e morfologia celular, a formalina interfere negativamente em testes de biologia molecular por fragmentar e modificar quimicamente os ácidos nucleicos, particularmente o ácido ribonucleico (RNA). OBJETIVO: Comparar a eficiência de três diferentes protocolos de extração de RNA para análise de expressão gênica de tecidos FFEP. MATERIAL E MÉTODOS: Amostras de linfonodo humano FEEP foram submetidas à extração de RNA utilizando-se os kits Ambion e Arcturus Bioscience e o método clássico de Trizol. Após a extração, o RNA foi quantificado e testado quanto à sua capacidade de amplificação pela reação em cadeia da polimerase em tempo real (RT-PCR) utilizando primers do gene endógeno gliceraldeído-3 fosfato desidrogenase (GAPDH). DISCUSSÃO/CONCLUSÃO: Todos os protocolos testados produziram quantidades adequadas e suficientes de RNA total, entretanto, somente os protocolos com uso dos kits Ambion e Arcturus produziram RNA capaz de ser amplificado pela PCR.

INTRODUCTION: Formalin fixed paraffin embedded (FFPE) tissues are an important sample source for retrospective studies. Despite its ability to preserve proteins and cell morphology, formalin hinders Molecular Biology tests once it fragments and chemically modifies nucleic acids, particularly RNA. OBJECTIVE: To compare the efficiency of three different RNA extraction protocols for gene expression analysis of FFEP tissues. MATERIAL AND METHODS: RNA was extracted from FFPE samples of human lymph by means of Ambion and Arcturus Bioscience kits and the classical Trizol method. After extraction, RNA was quantified and tested for amplification through real time polymerase chain reaction (RT-PCR) using glyceraldehydes-3 phosphate dehydrogenase (GAPDH) endogenous gene primers. DISCUSSION/CONCLUSION: All the protocols produced sufficient and adequate amounts of total RNA. However, only protocols using Arcturus and Ambion kits generated suitable RNA for PCR amplification.